K8SSAND-1602 ⁃ Remove defunctLabel checks

[burmanm]

What is missing?
Previously, cass-operator would not overwrite label values of generated resources if they were created before cass-operator 1.1.0. However, as that's no longer a supported version and also the fact that we do rewrite (and recreate) the StatefulSet labels these days, including the added created-by from #335 , we can also remove this check and simply rewrite the value to cass-operator.

Why do we need it?
Make label value changes consistent.

Environment

• Cass Operator version:

  Insert image tag or Git SHA here

  **Anything else we need to know?**:

┆Issue is synchronized with this Jira Task by Unito
┆friendlyId: K8SSAND-1602
┆priority: Medium