Operator should not depend on cluster.local domain

[juliusloman]

Describe the bug
Unable to run the operator when the cluster domain name is not cluster.local but other domain instead. Due to this, the operator does not start with the following error which is caused by the startup probe:

 Normal  Pulled    38s               kubelet           Successfully pulled image "docker.io/dynatrace/dynatrace-operator:v0.14.2" in 795ms (795ms including waiting)
 Warning Unhealthy 29s (x3 over 49s) kubelet           Startup probe failed: DNS service not ready: lookup kubernetes.default.svc.cluster.local on 10.96.0.10:53: no such host
 Normal  Killing   29s (x3 over 49s) kubelet           Container dynatrace-operator failed startup probe, will be restarted
 Warning BackOff   19s (x3 over 29s) kubelet           Back-off restarting failed container dynatrace-operator in pod dynatrace-operator-6787c7d8d-sstch_dynatrace(6e42c087-e503-4434-b29b-f4d4a1c2ee14)

To Reproduce
Just deploy Dynatrace Operator using standard means on a cluster with non-default cluster domain name.

Expected behavior
Dynatrace Operator should honor custom cluster domain name and the startup probe should take that into account.

Additional context
It's possible to comment out the startup probe in kubernetes.yaml as a workaround.

[chrismuellner]

Workaround exists for v0.14.x and default behavior will be adjusted for v0.15.0 to allow custom domains.