Fix DBError output in test logs
Fix DBError output in test logs

After patch If48ba9d3deb54f8e9ea1ed1987f832ddbaed33fc a (non-fatal) DBError
is displayed during unit tests run.
This patch fixes that by proper mocking (and stops mixing mock and mox
in single unit test).

Change-Id: I2bd857492d2fca7f3683f7b7a6b062e3dddcbeed

pratikmallya/heat,noironetworks/heat,jasondunsmore/heat,rdo-management/heat,pshchelo/heat,miguelgrinberg/heat,rdo-management/heat,gonzolino/heat,dragorosson/heat,rh-s/heat,miguelgrinberg/heat,cwolferh/heat-scratch,noironetworks/heat,srznew/heat,gonzolino/heat,dims/heat,srznew/heat,dragorosson/heat,openstack/heat,redhat-openstack/heat,jasondunsmore/heat,pratikmallya/heat,takeshineshiro/heat,openstack/heat,takeshineshiro/heat,cryptickp/heat,rh-s/heat,maestro-hybrid-cloud/heat,maestro-hybrid-cloud/heat,dims/heat,cwolferh/heat-scratch,cryptickp/heat,redhat-openstack/heat,pshchelo/heat,steveb/heat,steveb/heat