Fix nova notification on port unplug

Wrong event was send on port unplug which is
misleading, this patch fixes it.

Closes-Bug: #2112569
Change-Id: I95f50519f1eaf9023804bcd36a8b8e834b53d140
(cherry picked from commit ffc1509)

Author: karelyatin

neutron/plugins/ml2/drivers/ovn/mech_driver/mech_driver.py

@@ -1321,7 +1321,7 @@ def set_port_status_down(self, port_id):
 
             if self._should_notify_nova(db_port):
                 self._plugin.nova_notifier.record_port_status_changed(
-                    db_port, const.PORT_STATUS_ACTIVE, const.PORT_STATUS_DOWN,
+                    db_port, const.PORT_STATUS_DOWN, const.PORT_STATUS_ACTIVE,
                     None)
                 self._plugin.nova_notifier.send_port_status(
                     None, None, db_port)

neutron/tests/unit/plugins/ml2/drivers/ovn/mech_driver/test_mech_driver.py

@@ -1236,8 +1236,8 @@ def _test_set_port_status_down(self, is_compute_port=False):
             else:
                 self.mech_driver._plugin.nova_notifier.\
                     record_port_status_changed.assert_called_once_with(
-                        mock.ANY, const.PORT_STATUS_ACTIVE,
-                        const.PORT_STATUS_DOWN, None)
+                        mock.ANY, const.PORT_STATUS_DOWN,
+                        const.PORT_STATUS_ACTIVE, None)
                 self.mech_driver._plugin.nova_notifier.\
                     send_port_status.assert_called_once_with(
                         None, None, mock.ANY)