Refactor tests to reduce duplication

> @tthvo I addressed your feedback and added the tests to the Kubernetes branch as well. I have mostly avoided duplicating the tests if there are no logic changes between OpenShift and Kubernetes, but there actually is one in this case. The OAuth annotation is only present on OpenShift. I'm hoping after the release we can tidy up this test class a bit, it's very long. Perhaps we can avoid some copy-paste by using this `DescribeTable` Ginkgo feature: https://onsi.github.io/ginkgo/#table-specs?

Right! I was wondering that too. This Ginkgo feature would help a lot! I think we could file an issue for this?

_Originally posted by @tthvo in https://github.com/cryostatio/cryostat-operator/issues/458#issuecomment-1258464774_