Group and rename unit and integration tests to be aligned with our charm repos and to be operated via terraform

[merkata]

Our repos include two checks that are required to pass on PRs, where operator-workflows drifts from that and has a single check:

      ~ required_status_checks {
          ~ contexts = [
              - "check",
              + "integration-tests / Required Integration Test Status Checks",
              + "unit-tests / Required Test Status Checks",
            ]

The tests need to be grouped, so that this repo conforms to the structure of our charm repos and so that terraform can maintain that state.