Upgrade the team ROSA cluster to OCP 4.20, as it's been out for a while now and 4.21 is now available.

Same as before (e.g. https://issues.redhat.com/browse/RHIDP-11411), authorize the upgrade in OCM then upgrade the worker nodes after the control plane has been updated. Verify no operators / services are in an unready state after update.

In addition, for this upgrade, we should plan to upgrade RHOAI from 2.x to 3.x. This document https://access.redhat.com/articles/7133758 indicates that direct upgrades from 2.x are not supported. Instead, we'll need to do an uninstall and reinstall RHOAI 3.x with the model registry enabled