We need a test scenario to verify that rolling back the system works as expected

We can build a "fake 4.15" commit by building RPMs:

MICROSHIFT_VERSION=4.15.0-0 make rpms 

Flow:

1. Deploy/install system 4.14 MicroShift
2. Wait for system to be healthy (wait for greenboot to end and be green)
   1. /var/lib/microshift/version should contain 4.14.0
3. Rebase and reboot system to "fake 4.15"
4. System should be healthy, version should contain 4.15.0
5. Optionally create some K8s object like configmap, that should not exist after rolling back to 4.14

1. Run command: sudo rpm-ostree rollback and reboot the host
2. System should be healthy and MicroShift should be 4.14.0
3. after system with 4.14 is healthy, rollback again (to 4.15)
4. system with 4.15 should be healthy and k8s object created in step 5 should exist
   1. this verifies that we actually restored backup for 4.15 deployment, instead of just migrating from 4.14