[entities] celery-monitor: fix transition name for start

"running" is a state, not a transition.

entities.py

@@ -318,8 +318,8 @@ class CeleryTaskAdapter(ICeleryTask):
         transition = {
             STATES.SUCCESS: 'finish',
             STATES.FAILURE: 'fail',
-            STATES.STARTED: 'running',
-            'PROGRESS': 'running',
+            STATES.STARTED: 'start',
+            'PROGRESS': 'start',
         }.get(result.state)
         if transition is not None:
             log.info('<CeleryTask %s (task_id %s)> %s', task.eid, task_id,