This:

- brings consistency - no more mixing `_name_prefix` and `_registry_prefix`
- adds extensibility - a future patch will allow reconfiguring all registry prefixes for all roles in the playbook

We still have `_docker_` vs `_container_` inconsistencies.
These may be worked on later.

Related to:
- https://github.com/mautrix/meta/releases/tag/v0.4.0
- https://mau.fi/blog/2024-09-mautrix-release/

It seems like the new version does not support a `/metrics` endpoint.
We skip keep the Ansible variables, but they're not doing anything.

Shared Secret Auth double puppeting still works for these bridges, but
is deprecated and will go away in the future.

Related to: https://github.com/mautrix/facebook/issues/332

Fixes: https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3138