Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3701

We can restore support for it by making a non-/ path prefix trigger a
self-build with a modified build config, so that a Cinny version with
path-prefix support would be produced. Traefik label changes may also be
required.

For now, we're not doing all that work, but simply dropping support for path
prefixes for Cinny.

* Add a global config option for Docker network MTU

* Upgrade systemd_docker_base (v1.2.0-0 -> v1.3.0-0)

The new version includes `devture_systemd_docker_base_container_networks_driver_options`
due to 3cc7d12396

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3502

* Switch from passing matrix_playbook_docker_network_mtu to respecting devture_systemd_docker_base_container_networks_driver_options

Related to:
- 3cc7d12396
- https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3502

* Update all roles to versions that respect `devture_systemd_docker_base_container_networks_driver_options`

---------

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3333

commit cf8637efac
Author: Slavi Pantaleev <slavi@devture.com>
Date:   Sun Mar 24 19:14:57 2024 +0200

    Make devture_systemd_docker_base_ipv6_enabled automatically reconfigure geerlingguy/ansible-role-docker

    Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3218

commit dc7af3bc7d
Author: Slavi Pantaleev <slavi@devture.com>
Date:   Sun Mar 24 19:10:31 2024 +0200

    Replace matrix_ipv6_enabled with devture_systemd_docker_base_ipv6_enabled

    Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3218

commit 07e900d6a2
Author: Slavi Pantaleev <slavi@devture.com>
Date:   Sun Mar 24 19:01:51 2024 +0200

    Improve matrix_ipv6_enabled comments

commit 3f03ca7f69
Author: Tilo Spannagel <development@tilosp.de>
Date:   Sat Mar 9 19:27:50 2024 +0000

    Add setting to enable ipv6

Putting each client into its own network was good for isolation,
but it's quite wasteful in terms of the container network pool.

Previously, it had to go through matrix-nginx-proxy.
It's exposed to Traefik directly via container labels now

We expect `--tags=start` to handle systemd reloading, so we don't need
to do it manually each time we install/uninstall a .service file.

- forego removing Docker images - it's not effective anyway, because it
  only removes the last version.. which is a drop in the bucket, usually

- do not reload systemd - it's none of our business. `--tags=start`,
  etc., handle this

- combine all uninstall tasks under a single block, which only runs if
  we detect traces (a leftover systemd .service file) of the component.
  If no such .service is detected, we skip them all. This may lead to
  incorect cleanup in rare cases, but is good enough for the most part.

This paves the way for installing other roles into `roles/galaxy` using `ansible-galaxy`,
similar to how it's done in:

- https://github.com/spantaleev/gitea-docker-ansible-deploy
- https://github.com/spantaleev/nextcloud-docker-ansible-deploy

In the near future, we'll be removing a lot of the shared role code from here
and using upstream roles for it. Some of the core `matrix-*` roles have
already been extracted out into other reusable roles:

- https://github.com/devture/com.devture.ansible.role.postgres
- https://github.com/devture/com.devture.ansible.role.systemd_docker_base
- https://github.com/devture/com.devture.ansible.role.timesync
- https://github.com/devture/com.devture.ansible.role.vars_preserver
- https://github.com/devture/com.devture.ansible.role.playbook_runtime_messages
- https://github.com/devture/com.devture.ansible.role.playbook_help

We just need to migrate to those.