Goal:
Enhanced support for the ability to migrate a cluster from the ovn-kubernetes CNI plugin to the openshift-sdn CNI plugin.

Description:
Customers that need to migrate from the default CNI plugin of OpenShift 4.12+ (ovn-kubernetes) to the older openshift-sdn CNI plugin is expected to be rare, but non-zero. The possibility exists that a long-time user of openshift-sdn will opt to install or migrate to ovn-kubernetes for its new features, and after some time of use, determine it necessary to go back to openshift-sdn, for whatever reason. This Epic adds support for that "reverse" migration, and builds upon the logic currently used for rollbacks during the already-supported openshift-sdn to ovn-kubernetes migration process.