Until now, we were leaving services "enabled"
(symlinks in /etc/systemd/system/multi-user.target.wants/).

We clean these up now. Broken symlinks may still exist in older
installations that enabled/disabled services. We're not taking care
to fix these up. It's just a cosmetic defect anyway.

Expected to have regressed after https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1008

This patch comes with its own downsides (as described in the comments
for matrix_prometheus_node_exporter_container_http_host_bind_port),
but at least there's:
- no security issue
- metrics remain readable from matrix-prometheus (even if the network metrics are inaccurate)

A better patch is certainly welcome.

This reverts commit 68ca81c8c2.

Supposedly fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/907

Same reasoning as in 1cd251ed78

These validation tasks should only run when Prometheus is enabled.

Basic system stats, to show stuff the synapse metrics
can't show such as resource usage by bridges, etc

Seems to work fine as well.

This too has only been tested on debian amd64 so far

Initial attempt. Seems to work fine.

Only tested on debian amd64 so far