The node in a degraded state because of the use of a deleted machineconfig: machineconfig.machineconfiguration.openshift.io; rendered-$[custom-machine-config] not found in OpenShift 4.x

Issue

• Assigning a machineConfigPool to a node and then deleting by accident the machineConfig in use will put the node in a loopback trying to render the deleted machineConfig. It will cause discrepancies with the existing machineConfigPool to be in a degraded state.
• Deletion of a rendered machineConfig in use should never be done since it will lead to a degraded status of the node associated.
• The only other reason to lose a rendered config is a drift during install between the bootstrap and master generation.