Add e2e upgrade test for the operator

[tnozicka]

Is this a bug report or feature request?

• Feature Request

What should the feature do: For testing the current operator (vX.Y), it should:

• deploy operator vX.Y-1
• create a scyllacluster
• wait for it to deploy
• redeploy operator as vX.Y
• edit the scyllacluster to trigger a rollout
• wait for it do redeploy

What is use case behind this feature: We need to test N+1 upgrades for the operator.

An example of an issue we'll hit is the scyllacluster statefulset matchSelector that also uses a scylla version which differs when updated but statefulset selector is immutable. So when we start reconciling properly that's gonna be an issue that needs coverage and a workaround.