PR for appcat on fix/psql_encrypted_disk

[vshnbot]

Summary

There was a dependency loop that prevented the creation of VSHNPostgreSQL instances that use encrypted PVCs:

• The SGCluster object can't be created before the luks secret for the PVC is generated
• The luks secret can't be created without getting the instance count of the cluster object

This has been resolved by relying on the instance count from the composite and also waiting for the luks secrets to be present before attempting to access the sgcluster object to be able to override the storageClass for the PVCs

Checklist

• Categorize the PR by setting a good title and adding one of the labels:
  bug, enhancement, documentation, change, breaking, dependency
  as they show up in the changelog
• Update tests.
• Link this PR to related issues.

Link: vshn/appcat#236