Adjust MQ renaming script to keep old sts

In big environments/for novadeployment it takes some time, till all services /computenodes got rebuild and have the new MQ configured. In this time the operator should not be blocked, but e.g. nova-operator should still create new novacomputenodes. Also we want that if a pod fails/gets deleted, it gets recreated till step 4.

So we move the deletion of sts and serviceaccount to the end. Also the old AMQPServer gets relabeld (change component label), so the parent operator only finds the new Server and can continue.