Revise cluster_policy_get_by_type
Revise cluster_policy_get_by_type

When filters include enabled and policy_type, exact_filter can not
be used on ClusterPolicies directly, because policy_type is not
the property of ClusterPolicies.

Change-Id: Ief7dd8f59dddc7f17c7be875d86b662411fb4398
Related-Bug: 1634407

openstack/senlin,openstack/senlin,stackforge/senlin,openstack/senlin,stackforge/senlin