Standardize logging for v2 api extensions

- add log translation hints for warning, error and info levels
- remove pointless debug message

Change-Id: I67c5e77e62f8ef89204b67426b88856ef91dfc26

nova/api/openstack/compute/servers.py

@@ -606,8 +606,7 @@ class Controller(wsgi.Controller):
             msg = _('marker [%s] not found') % marker
             raise exc.HTTPBadRequest(explanation=msg)
         except exception.FlavorNotFound:
-            log_msg = _("Flavor '%s' could not be found ")
-            LOG.debug(log_msg, search_opts['flavor'])
+            LOG.debug("Flavor '%s' could not be found", search_opts['flavor'])
             # TODO(mriedem): Move to ObjectListBase.__init__ for empty lists.
             instance_list = objects.InstanceList(objects=[])