mgr/volumes/nfs: remove 'ganesha-' prefix from cluster id
Orchestrator defines service name as "<service_type>.<service_id>". The ganesha
common config object name in orchestrator is "conf-<service_name>". Volume's
nfs plugin deploys nfs-ganesha clusters with 'ganesha' prefixed to cluster id
and common config object. It can cause unecessary issues in rook and cephadm.
So let's remove the prefix.