Update all tests to use modern version of Cassandra

[burmanm]

What happened? We still have some tests that use 3.11 branch of Cassandra. Given that 3.11 is already EOL and we've stopped testing against it in cass-operator, it makes sense to remove all the tests in k8ssandra-operator also.

We should directly upgrade to 5.x instead since it should be a recommended version for most new deployments.

Did you expect to see something different?

How to reproduce it (as minimally and precisely as possible):

Environment

• K8ssandra Operator version:

  Insert image tag or Git SHA here

• Kubernetes version information:

  kubectl version

• Kubernetes cluster kind:

  insert how you created your cluster: kops, bootkube, etc.

• Manifests:

insert manifests relevant to the issue

• K8ssandra Operator Logs:

insert K8ssandra Operator logs relevant to the issue here

Anything else we need to know?:

┆Issue is synchronized with this Jira Story by Unito ┆Issue Number: K8OP-332