Don't allow deletion of the router ports without IP addresses

This patch effectively reverts old patch [1]. From now on it will be not
allowed to directly remove router ports which don't have fixed IPs
assigned. Such ports will be treated as any other ports connected to the
routers.
Originally [1] was introduced to allow cleanup of the router ports for
which subnets were deleted. But now it's not needed anymore as we
prevent deletion of subnet if there are any ports with IP allocated from
that subnet.

Closes-bug: #2025056

[1] https://review.opendev.org/c/openstack/neutron/+/20424

Change-Id: I1a3723ae999fefb5dcbe3a60cf1a4902da9f0265
(cherry picked from commit 32d589f)

Author: slawqo

neutron/db/l3_db.py

@@ -1730,15 +1730,6 @@ def prevent_l3_port_deletion(self, context, port_id, port=None):
             return
         if port['device_owner'] not in self.router_device_owners:
             return
-        # Raise port in use only if the port has IP addresses
-        # Otherwise it's a stale port that can be removed
-        fixed_ips = port['fixed_ips']
-        if not fixed_ips:
-            LOG.debug("Port %(port_id)s has owner %(port_owner)s, but "
-                      "no IP address, so it can be deleted",
-                      {'port_id': port['id'],
-                       'port_owner': port['device_owner']})
-            return
         # NOTE(kevinbenton): we also check to make sure that the
         # router still exists. It's possible for HA router interfaces
         # to remain after the router is deleted if they encounter an

neutron/tests/unit/db/test_l3_db.py

@@ -290,9 +290,10 @@ def test_prevent_l3_port_no_fixed_ips(self, gp):
         # without fixed IPs is allowed
         gp.return_value.get_port.return_value = {
             'device_owner': n_const.DEVICE_OWNER_ROUTER_INTF, 'fixed_ips': [],
-            'id': 'f'
+            'device_id': '44', 'id': 'f',
         }
-        self.db.prevent_l3_port_deletion(None, None)
+        with testtools.ExpectedException(n_exc.ServicePortInUse):
+            self.db.prevent_l3_port_deletion(mock.Mock(), None)
 
     @mock.patch.object(directory, 'get_plugin')
     def test_prevent_l3_port_no_router(self, gp):