QA tests for upgrade path for Kubernetes Integration

Since the gitlab-org/gitlab-qa~4196707 feature changes to Kubernetes need to support existing clusters configured in GitLab it would be beneficial to have integration tests that did something like:

1. Run previous release of GitLab
2. Create a cluster for a project (not installing cluster applications)
3. Upgrade to latest release of GitLab
4. Run all remaining steps of Auto DevOps test

This would have helped, for example, with preventing gitlab-com/gl-infra/production#566 (closed)

It would also be a bonus if it was easy for us to run these kinds of tests locally with arguments like PREVIOUS_VERSION and NEW_VERSION so that we can efficiently do our testing because right now the manual process for testing this kind of stuff is incredibly time consuming and error prone.