Stop gearman debug logging

Change-Id: I80f6851577cdb7f5aec35e9aee04e7bf1658e1a0
Reviewed-on: https://review.openstack.org/35387
Reviewed-by: Monty Taylor <mordred@inaugust.com>
Reviewed-by: Anita Kuno <anteaya@anteaya.info>
Approved: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins