This improves the behavior of health-checks
introducing two levels of them:

- service level: checks served by `sidekiq|web_exporter:'
  served on separate port

- application level: checks served by `/-/metrics` endpoint
  of `HealthController`

The changes makes the:

- `/liveness` always indicate that application is ready
  and not deadlocked
- `/readiness` to indicate:

The changes for `/readiness`:

- on service level: the status of the service if it can accept
  and process connections

- on application level: the status of external components if they
  are accessible

The `on service level` and `on application level` do not share
any checks, they have different checks exposed.