Add more ClusterClass tests to optional test suite #2796
Description
After #2793, we have a test that makes use of the ClusterClass. However, this class can be used in multiple ways so it would be good to verify at least one or two other ways. For example, we could test a "normal" ubuntu image without the ignition and sysext config. We could also test it with a bastion configured.
These tests should not be in the PR-blocking test, to avoid taking too much time. They can run in the full suite that runs periodically and can optionally be triggered on PRs.