db: Migrate "cluster" APIs to enginefacade
db: Migrate "cluster" APIs to enginefacade

Migrate cluster-related APIs from the legacy enginefacade to the modern
context-based enginefacade.

Change-Id: I89c339c3892ad6af436f48252844ffa03e6e854d
Signed-off-by: Stephen Finucane <4725dc7f3632bf126d9fbdc30c347e91e8d2fe16@redhat.com>

openstack/cinder,openstack/cinder,mahak/cinder,mahak/cinder