gabbi: set panko_is_disabled to avoid relying on Keystone autodiscovery
gabbi: set panko_is_disabled to avoid relying on Keystone autodiscovery

Change-Id: I8c8f9af899c4c5586b0bb6985c3b69ce6c48441b

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