Description of problem

To reduce QE load, we've decided to block up the hole drilled in OCPBUGS-24535. We might not want a pure revert, if some of the changes are helpful (e.g. more helpful error messages).

We also want to drop the oc adm upgrade rollback subcommand which was the client-side tooling associated with the OCPBUGS-24535 hole.

Version-Release number of selected component

Both 4.16 and 4.17 currently have the rollback subcommand and associated CVO-side hole.

How reproducible

Every time.

Steps to Reproduce

Try to perform the rollbacks that OCPBUGS-24535 allowed.

Actual results

They work, as verified in OCPBUGS-24535.

Expected results

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