After we migrated from Prometheus to VictoriaMetrics, we never attempted to remove prometheus.ini config for supervisor. If the User sequentially runs `supervisorctl stop all` and `supervisorctl start all`, they will notice that supervisor tried and failed to start Prometheus.
Later, when they try to print supervisord's status, they will see that supervisor has been relentlessly trying to launch prometheus' daemon, but all attempts failed, since on PMM versions starting from 2.12.0 `prometheus` is not installed.
This is definitely redundant and the User would benefit if we remove this noice from the system.
Remove prometheus.ini it from PMM.
- Leverage ansible to remove the package named percona-prometheus, which may have been kept on versions prior to 2.12.0
- Remove the generation of `prometheus.ini` config from `pmm-managed`, which is responsible for it now.
How to test:
- after executing `docker exec -it pmm-server sh -c "supervisorctl status"` against a running pmm-server, you should get:
- be sure that `prometheus` is not listed
- be sure that `prometheus.ini` is absent in `/etc/supervisord.d/`