Remove all discoverable policy rules

We have signaled many times the use of API extensions to change the API
has been deprecated, including:
04f8612aa99e618767a85d2f674ecdfc01955ff7

This patch ensures we no longer check any of the discoverable rules when
compiling the list of extensions to list in the API. This stops users
from being able to use policy to hide certain API extensions. This was
never that useful, but now you can't turn any extensions off and we
report the API version number, it is basically useless.

Note the change in the policy cmd unit test is to ensure now there are
no rules that use the ANY rule, we correctly check we return an empty
list of rules that match.

blueprint remove-discoverable-policy-rules

Change-Id: I61d8063708731133177534888ba7f5f05a6bd901

nova/policies/aggregates.py

@@ -13,8 +13,6 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-from oslo_policy import policy
-
 from nova.policies import base
 
 
@@ -42,9 +40,6 @@ aggregates_policies = [
                 'method': 'POST'
             }
         ]),
-    policy.RuleDefault(
-        name=POLICY_ROOT % 'discoverable',
-        check_str=base.RULE_ANY),
     base.create_rule_default(
         POLICY_ROOT % 'create',
         base.RULE_ADMIN_API,