upgrade to partitions without a costly bulk data migration

keep pre-upgrade events in an old table (instead of a partition)

- instead of creating a default partition, keep all events in special
"unpartitioned" tables
- track these tables via distinct proxy=true models
- when generating the queryset for a UnifiedJob's events, look at the
  creation date of the job; if it's before the date of the migration,
  query on the old unpartitioned table, otherwise use the more modern table
  that provides auto-partitioning

awx/api/views/inventory.py

@@ -51,9 +51,9 @@ class InventoryUpdateEventsList(SubListAPIView):
     search_fields = ('stdout',)
 
     def get_queryset(self):
-        return super(InventoryUpdateEventsList, self).get_queryset().filter(
-            job_created=self.get_parent_object().created_or_epoch
-        )
+        iu = self.get_parent_object()
+        self.check_parent_access(iu)
+        return iu.get_event_queryset()
 
     def finalize_response(self, request, response, *args, **kwargs):
         response['X-UI-Max-Events'] = settings.MAX_UI_JOB_EVENTS