Removed update reference from updating the provider stats

- single focus method
- allows not to pollute DAO with research mode

app/dao/notifications_dao.py

@@ -278,9 +278,13 @@ def dao_update_notification(notification):
 
 
 @transactional
-def update_notification_after_sent_to_provider(id_, notification_type, provider_name, reference=None):
-    provider = ProviderDetails.query.filter_by(identifier=provider_name).one()
+def update_provider_stats(
+        id_,
+        notification_type,
+        provider_name):
+
     notification = Notification.query.filter(Notification.id == id_).one()
+    provider = ProviderDetails.query.filter_by(identifier=provider_name).one()
 
     def unit_count():
         if notification_type == TEMPLATE_TYPE_EMAIL:
@@ -304,10 +308,6 @@ def update_notification_after_sent_to_provider(id_, notification_type, provider_
 
         db.session.add(provider_stats)
 
-    if reference:
-        notification.reference = reference
-        db.session.add(notification)
-
 
 def get_notification_for_job(service_id, job_id, notification_id):
     return Notification.query.filter_by(service_id=service_id, job_id=job_id, id=notification_id).one()