use common cache
use common cache

we shouldn't need to different cache between update and create as
it will create a larger cache and more calls[1]. there is only one
instance of a resource and it's hash will be relevant regardless
of action.

[1] https://review.openstack.org/#/c/203109/7/ceilometer/dispatcher/gnocchi.py

Change-Id: I7b469335f4914436510166abb1e18f5958e5c966

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