Description of problem

OTA-941 landed a rollback guard in 4.14 that blocked all rollbacks. OCPBUGS-24535 drilled a hole in that guard to allow limited rollbacks to the previous release the cluster had been aiming at, as long as that previous release was part of the same 4.y z stream. We decided to block that hole back up in OCPBUGS-35994. And now folks want the hole re-opened in this bug. We also want to bring back the oc adm upgrade rollback ... subcommand. Hopefully this new plan sticks

Version-Release number of selected component

Folks want the guard-hole and rollback subcommand restored for 4.16 and 4.17.

How reproducible

Every time.

Steps to Reproduce

Try to perform the rollbacks that OCPBUGS-24535 allowed.

Actual results

They stop working, with reasonable ClusterVersion conditions explaining that even those rollback requests will not be accepted.

Expected results

They work, as verified in OCPBUGS-24535.