ceph-disk: timeout ceph-disk to avoid blocking forever

ceph-disk: timeout ceph-disk to avoid blocking forever

When ceph-disk runs from udev or init script, it is in the background
and should it block for any reason, it may keep a lock forever. All
calls to ceph-disk in these context are changed to timeout.

The TimeoutStartSec= and TimeoutStopSec= which are both set via
TimeoutSec= do not apply to Type=oneshot services.

https://www.freedesktop.org/software/systemd/man/systemd.service.html

Fixes: http://tracker.ceph.com/issues/16580
Signed-off-by: Loic Dachary <loic@dachary.org>
(cherry picked from commit bed1a5cc05a9880b91fc9ac8d8a959efe3b3d512)