MAR-154: Update documentation and test site for Python 2.7 support removal:

- Drop most of the references to Python 2.
- Switch anything that has been previously using Python 2.7 to Python
3.

MAR-154: Improve incorrect Python version handling in virtual environments:

- This should be helpful when performing distribution upgrades as
well (since it should be able to automatically detect a mismatch
now).

MAR-154: Drop suppor for Python 2.7 from the wsgi_website role:

- Mostly a matter of dropping the Python version parameter, and
updating some package versioning to account for Python 3 only.

MAR-154: Drop support for Python 2.7 from the common role:

- This primarily concerns removal of pip requirements upgrade checks
for Python 2.7.
- The old Python 3-specific paths are getting deprecated, and the
Python 2 paths will be used instead.
- Set permissions on pipreqcheck directory explicitly (because of
deprecation testing).

MAR-191: Using pexpect+sftp still required for Duplicity backup:

- From what I can tell even Debian 11 Bullseye duplicyt has similar
limitation like the Buster version.

MAR-191: Drop support for Debian 11 Buster from the wsgi_website role:

- Get rid of the workaround that used to cause issues in some of the
previous versions of Debian while at it. This should no longer pose
an issue.

MAR-191: Drop support for Debian 10 Buster from the php_website role:

- Move some of the distribution release-specific information used in
tests into a fixture of its own. Make the code a bit cleaner/more
consistent.

MAR-191: Drop support for Debian 10 Buster from the common role:

- Fix incorrect comment on the pkg-resources/pkg_resources package as
well - this one is not distro-dependent.

MAR-191: Make tests for allowed/disallowed connections more generic:

- Use dynamic inventory to retrive the list of hosts instead of
hard-coding release names in the tests.

MAR-191: Drop Debian 10 Buster support for the backup_client role:

- Internal parameter for Python's pexpect package is no longer
required - newer versions of Debian have fully switche to using the
Python 3 version of it for duplicity.
- Fix prepare playbook task to iterate over list of backup users
instead of hard-coding the values.
- Drop the directory set-up task that seems to serve no purpose (some
leftover from previous refactoring most likely.
- Update supported version information in docs and metadata.

MAR-193: Fix deprecation warnings coming from newer versions of pip-tools:

- In more recent versions of pip-tools, a new option has been
added (--strip-extras) that will become a new default in next major
release. Not using this option causes some warnings on Debian 11
Bullseye when pip-tools is brought up to date.
- Refactor the invocation of pip-compile to make it more modular.
- No test expansion for this since it would make it a bit harder to
target both Debian 10 Buster and Debian 11 Bullseye.

MAR-193: Updated requirements file for up-to-date version of Python:

- Primarily required in order to run Gimmecert in tests.

MAR-193: Fix deprecation warnings coming from newer versions of pip-tools:

- In more recent versions of pip-tools, a new option has been
added (--strip-extras) that will become a new default in next major
release. Not using this option causes some warnings on Debian 11
Bullseye when pip-tools is brought up to date.
- Refactor the invocation of pip-compile to make it more modular.
- No test expansion for this since it would make it a bit harder to
target both Debian 10 Buster and Debian 11 Bullseye.

MAR-193: Updated requirements file for up-to-date version of Python:

- Primarily required in order to run Gimmecert in tests.

MAR-189: Disable use of KVM paravirtualisation provider with Vagrant/VirtualBox:

- The VMs seem to randomly hang when the (KVM) clock source gets
initialised right after getting past the bootloader. Helps run the
tests in a way more reliable way.
- Should be removed if upgrading to latest kernel/VirtualBox versions
helps.

MAR-189: Replace The Bug Genie deployment as part of usage instructions with Nextcloud:

- Nextcloud is still being properly maintained, and should be way less
hacky to roll-out as opposed to TBG.

MAR-189: Drop development upgrade instructions for Molecule/Testinfra:

- This has been done long time ago, and it's just a leftover artifact
at this point (has no real value any longer).

MAR-189: Drop the deprecaetd/unknown mutt options for test site:

- No longer works at least with mutt version coming with Debuan 10
Buster.

MAR-189: Updated instructions and configuration for test site for Debian 11 Buster:

- Use a more generic Emacs package name.

MAR-189: Rework fix for legacy iptables and ferm:

- Unfortunately, using diversions with iptables legacy binaries does
not work correctly because the iptables package will try to run
update-alternatives on install/upgrade, and error out because the
files are not available in the original locations.
- Divert the ferm binary instead, and roll-out a custom patched
version of it instead.
- Use a custom script to drop the legacy iptables (for both IPv4 and
IPv6).
- Update the tests accordingly.

MAR-189: Refactor test for additional SMTP server configuration:

- Use different override to avoid Postfix warnings about overridden
configuration option in the same file.

MAR-189: Added support for Debian 11 Bullseye to mail_server role:

- Shorten the backup client username so it would be under 32
characters.
- Switch all helper VMs to using the Debian 11 Bullseye as well.
- Drop the architecture suffix from hostnames.
- Update the hostname for client VMs.
- Fix the incorrect format for the message ID used in various mail
delivery tests.

MAR-189: Merge some configuration changes from Debian Bullseye for mail server configuration files:

- Get rid of using the session cache databases for TLS for smtpd -
this is no longer the preferred way to handle it (RFC 5077 TLS
session tickets should be used).
- Indicate that the delivery through external commands is final (X
flag of the pipe(8) mechanism). Affects the delivery status
notifications, changing them from "relayed" to "delivered".

MAR-189: Added support for Debian 11 Bullseye to xmpp_server role:

- Roll-out LDAP client configuration since Bullseye does not come with
a stock one at /etc/ldap/ldap.conf that sets the trust anchor
correctly for validating LDAP server certificates.
- Drop the backports pinning in case of Bullseye (for now let's try to
keep the Buster and Bullseye at same versions for simplicity).
- Drop installation of Python apt bindings (no longer used).
- Tests for Buster and Bullseye need to be split-up a bit due to some
differences around backports etc.

MAR-189: Dropped deprecation-related tasks and tests for xmpp_server role:

- Migration from Prosody project repositories should have been done
already as part of the 7.0.1 release.
- Simplifies the code a bit.
- Drop leftover deprecated library plugin path.

MAR-189: Refactored web_server tests to be less hostname-dependent:

- Use the inventory name (alongisde distribution version) in places
where it's possible and makes sense to do so.
- Rearrange the IP allocation a bit to make more sense.
- Drop architecture information from the hostnames.
- Make the connectivity test operate over a matrix of input
parameters.
- Replace singular use of wget for testing with curl.

MAR-189: Refactored admin acocunt handling in the ldap_server role:

- Get rid of the admin entry from the directory, and resort to using
the directory's olcRootDN/olcRootPW attributes instead. Aligns
Buster package deployment with Bullseye one, as implemented via fix
for the following Debian bug:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=821331

- Add the helper filter plugin to deal with calculating the salted
SHA1 checksum.
- Drop the architecture from Molecule instance names.
- Move the IPs around a tiny bit for Molecule instances.

MAR-189: Remove deprecation-related tasks and tests for database_server role:

- These were relevant in some older versions of Debian and needed
during upgrades from versions that still employed passwords for
system logins/tasks.

MAR-189: Added support for Debian 11 Bullseye to backup_server role:

- Drop the architecture version from the test machine names.

MAR-189: Disable the legacy iptables tools by effectively renaming them:

- Somewhat more forceful but better way to deal with ferm in Bullseye
explicitly using the legacy tools for some unspecified compatibility
reasons.
- Renders the tools unusable because the calling name has
changed (they are all symlinks to the same file).
- Not necessarily required on Debian Buster, but it also won't cause
any damage there either.

MAR-189: Added support for Debian 11 Bullseye to common role:

- Drop the architecture suffix from all machines.
- Introduced a hack/patch for Ferm utility that disables use of legacy
iptables tools.
- Minor fixes around package name differences compared to older
distribution.
- Use versioned binary name for Python 2.7.. Bullseye does not
default/have /usr/bin/python pointing to Python 2.7 binary.

MAR-189: Added support for Debian 11 Bullseye to backup role:

- Drop the 64-bit architecture indiactor from the VMs.

MAR-189: Added support for Debian 11 Bullseye to backup_client role:

- Duplicity on Buster and Bullseye uses different Python version (2 vs
3), install the correct Python pexpect package.
- Switch the helper backup server to using Bullseye, and tweak its
SSHD configuration accordingly.

MAR-189: Refactor hostname pattern for backup_client role (buster/bullseye/bookworm):

- Multiple releases one after the other have names that begin with
letter b, making it necessary to use more than just one letter.
- Use full distro codename, but shorten the parameters to param in
order to avoid issues related to 32-character username limits (when
bak-HOSTNAME user gets created).
- Drop some leftover references to Debian Stretch.
- Drop the arch from hostnames - default is to use 64-bit boxes
anyway.

MAR-187: Reorder the deprecation tasks for xmpp_server role to make the runs reliable:

- Deprecated apt repository really needs to be removed first in case
it has an unresolvable URL (so the backports repository cache update
would trigger correctly).
- Use the file removal for Prosody repository as well to make sure the
file is dropped.

MAR-186: Reorder the deprecation tasks for xmpp_server role to make the runs reliable:

- Deprecated apt repository really needs to be removed first in case
it has an unresolvable URL (so the backports repository cache update
would trigger correctly).
- Use the file removal for Prosody repository as well to make sure the
file is dropped.

MAR-185: Fix the commit command used during the release process:

- The alias commits is no longer used, and OpenPGP signatures are
implemented via git configuration instead.

MAR-183: Use local caching and serving of ClamAV database files:

- Helps avoid getting stuck due to hitting the upstream rate limiting,
and also speeds-up the database downloads.

MAR-183: Drop the create/destroy playbooks for Molecule tests:

- These playbooks are automatically populated by Molecule runs, and
only useful changing in very specific circumstances.
- Solves issues about some missing functionality due to oudated
playbook code (like mounting of share directory on host with
Vagrant).

MAR-184: Update package versions for pip upgrade checks virtual environments:

- Should provide better test coverage compared to previously since
newer versions of pip-tools have slightly different ways of resolving
packages, as well as output formats.

MAR-182: Added ability to specify input requirements for running pip package upgrade checks against helper virtual environments:

- These environments are used for running the package upgrade checks
themselves.

MAR-181: Refactor the Prosody package version checks:

- Move the Prosody package version check into default set of tests.

MAR-181: Deploy Prosody modules (in order to use the LDAP authentcation):

- Replaces the rolled-out-by-hand authentication module, making it
less dependent on upstream repository.

MAR-181: Install Prosody from Debian backports repository:

- This way we should be able to get way more features available, and
reduce chances of breaking upgrades from upstream project towards
Debian-provided packages due to eventual bigger differences between
the nightly builds and official releases.