Apply conservative database connection reduction changes (#14066)

This is expected to free up 4 additional database connections per traditional node
  compare to roughly 12 in total before this change

Out of these 3 are accomplished by using existing connection for recently added services
  then 1 is obtained by closing the connection for the idle callback receiver main process

Signed-off-by: jessicamack <jmack@redhat.com>
Co-authored-by: jessicamack <jmack@redhat.com>

awx/main/dispatch/worker/base.py

@@ -143,9 +143,10 @@ class AWXConsumerRedis(AWXConsumerBase):
     def run(self, *args, **kwargs):
         super(AWXConsumerRedis, self).run(*args, **kwargs)
         self.worker.on_start()
+        logger.info(f'Callback receiver started with pid={os.getpid()}')
+        db.connection.close()  # logs use database, so close connection
 
         while True:
-            logger.debug(f'{os.getpid()} is alive')
             time.sleep(60)