Fix: pacemaker-remote: pacemaker_remoted shutdown while unmanaged

Since introduction of the graceful shutdown of pacemaker_remoted
the shutdown is hanging if the remote-resource is unmanaged.
This happens as pacemaker_remoted is waiting for all resources
running on the remote-node to be shut down and pacemaker
on the other hand doesn't touch resources on a remote-node
when the remote-resource is unmanaged.

Fixes rhbz#1388102