Ensure that stale flows are cleaned from phys_bridges

In case when neutron-ovs-agent will notice that any of physical
bridges was "re-created", we should also ensure that stale Open
Flow rules (with old cookie id) are cleaned.
This patch is doing exactly that.

Conflicts:
    neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py

Change-Id: I7c7c8a4c371d6f4afdaab51ed50950e2b20db30f
Related-Bug: #1864822
(cherry picked from commit 63c45b3766)

neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py

@@ -2303,6 +2303,10 @@ class OVSNeutronAgent(l2population_rpc.L2populationRpcCallBackTunnelMixin,
                     bridges_monitor.bridges_added + self.added_bridges)
                 bridges_recreated = self._reconfigure_physical_bridges(
                     added_bridges)
+                if bridges_recreated:
+                    # In case when any bridge was "re-created", we need to
+                    # ensure that there is no any stale flows in bridges left
+                    need_clean_stale_flow = True
                 sync |= bridges_recreated
             # Notify the plugin of tunnel IP
             if self.enable_tunneling and tunnel_sync:
@@ -2361,14 +2365,19 @@ class OVSNeutronAgent(l2population_rpc.L2populationRpcCallBackTunnelMixin,
                                 ovs_restarted or bridges_recreated)
                         failed_devices = self.process_network_ports(
                             port_info, provisioning_needed)
-                        if need_clean_stale_flow:
-                            self.cleanup_stale_flows()
-                            need_clean_stale_flow = False
                         LOG.info("Agent rpc_loop - iteration:%(iter_num)d - "
                                  "ports processed. Elapsed:%(elapsed).3f",
                                  {'iter_num': self.iter_num,
                                   'elapsed': time.time() - start})
 
+                    if need_clean_stale_flow:
+                        self.cleanup_stale_flows()
+                        need_clean_stale_flow = False
+                        LOG.info("Agent rpc_loop - iteration:%(iter_num)d - "
+                                 "cleanup stale flows. Elapsed:%(elapsed).3f",
+                                 {'iter_num': self.iter_num,
+                                  'elapsed': time.time() - start})
+
                     ports = port_info['current']
 
                     if self.ancillary_brs: