configurator: use sanlock user constant

Replace the static value with a constant.

Change-Id: I43464961cba6b6b761a98ad4b72a271228914ca1
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/26080
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>