tests: resolve ceph-helpers races

Some tests were racing against the monitor. On a fast machine it worked
but slower machines (or sometime when running in parallel), the monitor
is lagging behind. Use wait_for_clean to make sure the monitor is in the
desired state for the test to succeed.

http://tracker.ceph.com/issues/10384 Fixes: #10384

Signed-off-by: Loic Dachary <ldachary@redhat.com>
init-ceph: stop returns before daemons are dead

The existence of the pidfile must be checked outside of the loop to send
a signal to the daemon. Otherwise the daemon will remove the pidfile and
stop can return before the process is dead because it only checks
/proc/$pid if the pidfile exists.

http://tracker.ceph.com/issues/10389 Fixes: #10389

Signed-off-by: Loic Dachary <ldachary@redhat.com>