constants: remove unuesd service constant

Use have been moved to service.py

Change-Id: Ib8b1d0d45fa43a106db0a7fc3189503d4ee12890
Signed-off-by: Yeela Kaplan <ykaplan@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/35779
Reviewed-by: Dan Kenigsberg <danken@redhat.com>