This patch hopefully fixes issues with sending kill signals to subprocesses from the master process of dovecot.

Exmaple error logs:
```
Jan 25 00:27:16 master: Error: service(auth): kill(14, SIGINT) failed: Operation not permitted
Jan 25 00:28:16 master: Error: service(auth): Process 14 is ignoring idle SIGINT
```

This patch moves the dovecot config from the container build to the helm
chart which allows to use templating with values that are configured at
runtime. This should provide more flexibility and standardizes the
dovecot container further.

This patch updates the link to the helm repository for AMD GPU drivers
after AMD changed Github organisation names.

This patch adds a readinessProbe to the quorum pods, this causes the
kubelet to test the etcd health endpoint, resulting in proper status of
the etcd node, and therefore keeping the quorum. This should help to
improve cluster stablility.