[OVN] Add a log message after the "post_fork_initialize" method

Related-Bug: #2036607
Change-Id: I84a7a6cff5921488686ebf9ab95aa270d22b4e31
(cherry picked from commit 236f8d0)

Author: ralonsoh

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

@@ -390,6 +390,9 @@ def post_fork_initialize(self, resource, event, trigger, payload=None):
             self._maintenance_thread.start()
             LOG.info("Maintenance task thread has started")
 
+        LOG.info('%s process has finished the post initialization',
+                 worker_class.__name__)
+
     def _create_security_group_precommit(self, resource, event, trigger,
                                          payload):
         context = payload.context