This moves the comments from being just in Jinja,
to actually ending up in the generated `labels` file,
which makes inspection of the final result easier.

Also, some new lines were added here and there to make labels
more legible.

The generated file may still include weird new-lines due to
various `if` statements yielding content or not, but that's not so ugly
anymore - now that we have proper start/end sections that are visible in
the final `labels` file.

This is an attempt at optimizing service startup.

The effect is most pronounced when many services are restarted one by one.
The systemd service manager role sometimes does this - for example when `just install-service synapse` runs.
In such cases, a 5-second delay for each Synapse worker service
(or other bridge/bot service that waits on the homeserver) quickly adds up to a lot.

When services are all stopped fully and then started, the effect is not so pronounced, because
`matrix-synapse.service` starts first and pulls all worker services (defined as `Wants=` for it).
Later on, when the systemd service manager role "starts" these worker services, they're started already.
Even if they had a 5-second wait each, it would have happened in parallel.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3090

Related to https://github.com/mautrix/signal/issues/422

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3088

Looks like the migration to the Go-based Signal bridge hardcoded the
`signalbot` username instead of using the variable we had.
Related to: https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3041

* chore(deps): update signal bridge version + config

* style(deps): rename default note to self config variable

* Add to_json for additional safety

---------

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

Fixes: https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3082

Related to: https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3079

.. because matrix_mautrix_signal_version is used in other places
which do not expect it. For example: `matrix_mautrix_signal_container_image_self_build_branch`

Related to: https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3041

0.23.1 no longer syncs groups properly, the solution is to use 0.23.2, which works as expected

* one var to control encryption across all bridges

* move var to matrix-base

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/2427

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/2427

`metrics_enabled` should only expose the metrics locally, on the
container network, so that a local Prometheus can consume them.

Exposing them publicly should be done via a separate toggle (`metrics_proxying_enabled`).
This is how all other roles work, so this makes these mautrix roles consistent with the rest.

Fixes the following issue when trying to use the !pm <phone number> command: https://gitlab.com/signald/signald/-/issues/345

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 was useful when the order of these roles in relation to Synapse
mattered (when we were injecting stuff into Synapse variables during
runtime). This is no longer the case since 0ea7cb5d1812a88, so all of
this can be removed.