This supersedes/fixes-up this Pull Request:
https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/719

The Jitsi Web and JVB containers now (in build 5142) always
start by bulding their own default configuration
(`config.js` and `sip-communicator.properties`, respectively).

The fact that we were generating these files ourselves was no longer of use,
because our configuration was thrown away in favor of the one created
by the containers on startup.

With this commit, we're completely redoing things. We no longer
generate these configuration files. We try to pass the proper
environment variables, so that Jitsi services can generate the
configuration files themselves.

Besides that, we try to use the "custom configuration" mechanism
provided by Jitsi Web and Jitsi JVB (`custom-config.js` and
`custom-sip-communicator.properties`, respectively), so that
we and our users can inject additional configuration.

Some configuration options we had are gone now. Others are no longer
controllable via variables and need to be injected using
the `_config_extension` variables that we provide.

The validation logic that is part of the role should take care
to inform people about how to upgrade (if they're using some custom
configuration, which needs special care now). Most users should not
have to do anything special though.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/735

Also switches to using `docker system prune -a` for a less invasive
cleanup of Docker images and related resources.

Related to #681 (Github Pull Request)

Related to #681 (Github Pull Request)

Related to #681 (Github Pull Request)

This broke in 63a49bb2dc.

Proxying the OpenID Connect endpoints is now possible,
but needs to be enabled explicitly now.

Supersedes #702 (Github Pull Request).

This patch builds up on the idea from that Pull Request,
but does things in a cleaner way.

Regression since 63a49bb2dc.

Related to #685 (Github Issue).

We now automatically expose the APIs when Synapse Admin is enabled.

The SSL certificates should be accessible to the nginx proxy container, not the synapse container.

Discussed in #669 (Github Issue).

Interestingly, no one has reported this failure before #662 (Github
Issue).

It doesn't make sense to keep saying that we support such old Ansible
versions, when we're not even testing on anything close to those.

Time is also passing and such versions are getting more and more
ancient. It's time we bumped our requirements to something that is more
likely to work.

Improved formatting for a header that was attached to the previous paragraph (...by inserting a newline).

modified example for jitsi ldap authentication to show all available variables.

Change anonymized to more proper term as server vice this is not anonymized. Server name is the first parameter that is collected. And if server happens to be for individual use these statistics would be at personal level without any anonymising.

We recently had a report of the Postgres backup container's log file
growing the size of /var/lib/docker until it ran out of disk space.

Trying to prevent similar problems in the future.

Related to #620 (Github Pull Request).

Potentially the CURLing could be a better approach, since then you don't leave spare sessions hanging.