Fix namespace removal

[Miles-Garnsey]

What this PR does:

When I merged #387 it looked like all tests were passing but the multi-cluster tests just hadn't run. They all fail!

This is because the data plane kustomizations were wrong - they applied the same deletion patch that was already applied in the control-plane kustomizations from which data-plane is derived. Because the namespace is already deleted, this causes an error in kustomize build.

Which issue(s) this PR fixes:

Haven't raised one, this is a hotfix.

Checklist

• Changes manually tested
• Automated Tests added/updated
• Documentation added/updated
• CHANGELOG.md updated (not required for documentation PRs)
• CLA Signed: DataStax CLA

[Miles-Garnsey]

I think this is good to merge despite some test failures:

• ClusterScoped/MultiDcMultiCluster - has been failing consistently for some time.
• CreateSingleDatacenterCluster - failed due toINSTALLATION FAILED: Service "traefik" is invalid: spec.ports[3].nodePort: Invalid value: 30080: provided port is already allocated This is likely something to do with a previous test not cleaning up after itself properly.
• CreateSingleReaper this fails due to Reaper not being cleaned up properly. It was failing as of commit 595c2c3bca6660c708f72f1b940c686b9ec76e03 which was prior to my merge that broke the multi-cluster e2e tests this morning.
• StopAndRestartDc consistently fails in most PRs at the moment.