Since we can't know at service start how many VMs will be running we
can't calculate an apropriate shutdown timeout. So instead of killing
off the service just let it use it's own internal timeout mechanism.
References:
http://bugs.debian.org/803714https://bugzilla.redhat.com/show_bug.cgi?id=1195544
(cherry picked from commit ba08d16d6cec81656b333435650aef36a012034c)