Issues and Pull Requests were not migrated to the new
organization/repository, so `matrix-org/synapse/pull` and
`matrix-org/synapse/issues` references were kept as-is.

`matrix-org/synapse-s3-storage-provider` references were also kept,
as that module still continues living under the `matrix-org` organization.

This patch mainly aims to change documentation-related things, not actual
usage in full yet. For polish that, another more comprehensive patch is coming later.

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 was meant to serve as an intermediary for services needing to reach
the homeserver. It was used like that for a while in this
`bye-bye-nginx-proxy` branch, but was never actually public.

It has recently been superseded by homeserver-like services injecting
themselves into a new internal Traefik entrypoint
(see `matrix_playbook_internal_matrix_client_api_traefik_entrypoint_*`),
so `matrix-homeserver-proxy` is no longer necessary.

---

This is probably a good moment to share some benchmarks and reasons
for going with the internal Traefik entrypoint as opposed to this nginx
service.

1. (1400 rps) Directly to Synapse (`ab -n 1000 -c 100 http://matrix-synapse:8008/_matrix/client/versions`
2. (~900 rps) Via `matrix-homeserver-proxy` (nginx) proxying to Synapse (`ab -n 1000 -c 100 http://matrix-homeserver-proxy:8008/_matrix/client/versions`)
3. (~1200 rps) Via the new internal entrypoint of Traefik (`matrix-internal-matrix-client-api`) proxying to Synapse (`ab -n 1000 -c 100 http://matrix-traefik:8008/_matrix/client/versions`)

Besides Traefik being quicker for some reason, there are also other
benefits to not having this `matrix-homeserver-proxy` component:

- we can reuse what we have in terms of labels. Services can register a few extra labels on the new Traefik entrypoint
- we don't need services (like `matrix-media-repo`) to inject custom nginx configs into `matrix-homeserver-proxy`. They just need to register labels, like they do already.
- Traefik seems faster than nginx on this benchmark for some reason, which is a nice bonus
- no need to run one extra container (`matrix-homeserver-proxy`) and execute one extra Ansible role
- no need to maintain a setup where some people run the `matrix-homeserver-proxy` component (because they have route-stealing services like `matrix-media-repo` enabled) and others run an optimized setup without this component and everything needs to be rewired to talk to the homeserver directly. Now, everyone can go through Traefik and we can all run an identical setup

Downsides of the new Traefik entrypoint setup are that:

- all addon services that need to talk to the homeserver now depend on Traefik
- people running their own Traefik setup will be inconvenienced - they
  need to manage one additional entrypoint

We'd be adding integration with an internal Traefik entrypoint
(`matrix_playbook_internal_matrix_client_api_traefik_entrypoint`),
so renaming helps disambiguate things.

There's no need for deperecation tasks, because the old names
have only been part of this `bye-bye-nginx-proxy` branch and not used by
anyone publicly.

This allows us to eliminate the companion and decrease overhead for
simple servers which do not use workers.

This also updates validation tasks and documentation, pointing to
variables in the matrix-synapse role which don't currently exist yet
(e.g. `matrix_synapse_container_labels_client_synapse_admin_api_enabled`).

These variables will be added soon, as Traefik labels are added to the
`matrix-synapse` role. At that point, the `matrix-synapse-reverse-proxy-companion` role
will be updated to also use them.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/2444

Switching from doing "post-start" loop hacks to running the container
in 3 steps: `create` + potentially connect to additional networks + `start`.
This way, the container would be connected to all its networks even at
the very beginning of its life.

* add prometheus-nginxlog-exporter role

* Rename matrix_prometheus_nginxlog_exporter_container_url to matrix_prometheus_nginxlog_exporter_container_hostname

* avoid referencing variables from other roles, handover info using group_vars/matrix_servers

* fix: stop service when uninstalling

fix: typo

move available arch's into a var

fix: text

* fix: prometheus enabled condition

Co-authored-by: ikkemaniac <ikkemaniac@localhost>

- 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.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/2090