Close #496 Splited from #932

This improves the compatibility and makes it easier to work with various tools, which take advantake from the assumption of existence of those labels.

• https://helm.sh/docs/chart_best_practices/labels/
• https://kubernetes.io/docs/concepts/overview/working-with-objects/common-labels/

Keep the old labels for selectors for backward compatibility.

Also note there is slight change in behaviour of PDB which might be backward-incompatible in some rare cases, but it is IMHO edge-case when the release name changes and someone for some obscure reason depends on not scheduling the new pods to same K8s node as the old pod, so I consider this change benign.

The chart was tested with the following values:

reloader:
  deployment:
    replicas: 2
    priorityClassName:
  enableHA: true
  logFormat: json
  podDisruptionBudget:
    enabled: true
  podMonitor:
    enabled: true
  readOnlyRootFileSystem: true
  reloadOnCreate: true