use qos default api def from neutron-lib

Commit If59765fe1f293d4ca6f80f62b22a420a388dfb68 rehomed the qos default
extension's API definition into neutron-lib. This patch consumes it
by removing the rehomed code and using lib's API definition instead.

NeutronLibImpact

Change-Id: Ifd29134de594ee64941361195c50dac664c5b6b1

neutron/extensions/qos_default.py

@@ -13,67 +13,10 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-from neutron_lib.api import converters
-from neutron_lib.api.definitions import qos as qos_apidef
+from neutron_lib.api.definitions import qos_default as apidef
 from neutron_lib.api import extensions
 
 
-# The alias of the extension.
-ALIAS = 'qos-default'
+class Qos_default(extensions.APIExtensionDescriptor):
 
-# The name of the extension.
-NAME = 'QoS default policy'
-
-# The description of the extension.
-DESCRIPTION = 'Expose the QoS default policy per project'
-
-# A timestamp of when the extension was introduced.
-TIMESTAMP = '2017-041-06T10:00:00-00:00'
-
-# The list of required extensions.
-REQUIRED_EXTENSIONS = [qos_apidef.ALIAS]
-
-# The list of optional extensions.
-OPTIONAL_EXTENSIONS = None
-
-# The resource attribute map for the extension.
-RESOURCE_ATTRIBUTE_MAP = {
-    qos_apidef.POLICIES: {
-        'is_default': {'allow_post': True,
-                       'allow_put': True,
-                       'default': False,
-                       'convert_to': converters.convert_to_boolean,
-                       'is_visible': True}
-    }
-}
-
-
-class Qos_default(extensions.ExtensionDescriptor):
-
-    @classmethod
-    def get_name(cls):
-        return NAME
-
-    @classmethod
-    def get_alias(cls):
-        return ALIAS
-
-    @classmethod
-    def get_description(cls):
-        return DESCRIPTION
-
-    @classmethod
-    def get_updated(cls):
-        return TIMESTAMP
-
-    def get_required_extensions(self):
-        return REQUIRED_EXTENSIONS or []
-
-    def get_optional_extensions(self):
-        return OPTIONAL_EXTENSIONS or []
-
-    def get_extended_resources(self, version):
-        if version == "2.0":
-            return RESOURCE_ATTRIBUTE_MAP
-        else:
-            return {}
+    api_definition = apidef