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/management/commands/run_cache_clear.py

@@ -2,6 +2,7 @@ import logging
 import json
 
 from django.core.management.base import BaseCommand
+
 from awx.main.dispatch import pg_bus_conn
 from awx.main.dispatch.worker.task import TaskWorker
 
@@ -18,7 +19,7 @@ class Command(BaseCommand):
 
     def handle(self, *arg, **options):
         try:
-            with pg_bus_conn(new_connection=True) as conn:
+            with pg_bus_conn() as conn:
                 conn.listen("tower_settings_change")
                 for e in conn.events(yield_timeouts=True):
                     if e is not None: