Purge cleanup_deleted tasks as they aren't needed

This also adds a periodic static task to cleanup auth tokens

awx/settings/defaults.py

@@ -349,6 +349,10 @@ CELERYBEAT_SCHEDULE = {
         'task': 'awx.main.tasks.run_label_cleanup',
         'schedule': timedelta(days=7)
     },
+    'authtoken_cleanup': {
+        'task': 'awx.main.tasks.cleanup_authtokens',
+        'schedule': timedelta(days=30)
+    },
 }
 
 # Social Auth configuration.