fix tempest path
fix tempest path

the path for tempest tests are incorrect. this ends up breaking
magnum gate magnum already has tempest plugin support

Change-Id: Ie58d6c15b5640bef73662f6427f0b07886f1a859

idegtiarov/ceilometer,ityaptin/ceilometer,idegtiarov/ceilometer,ityaptin/ceilometer,openstack/ceilometer,openstack/ceilometer