remove jobs from letter api and make success/error ftp callback tasks

1. No longer create jobs when creating letters from api 🎉
2. Bulk update notifications based on the notification references after
   we send them to DVLA - either as success or as error

app/dao/notifications_dao.py

@@ -475,15 +475,19 @@ def dao_update_notifications_for_job_to_sent_to_dvla(job_id, provider):
 
 @statsd(namespace="dao")
 @transactional
-def dao_update_notifications_by_reference_sent_to_dvla(notification_references, provider):
+def dao_update_notifications_by_reference(references, update_dict):
     now = datetime.utcnow()
-    updated_count = db.session.query(
-        Notification).filter(Notification.job_id == job_id).update(
-        {'status': NOTIFICATION_SENDING, "sent_by": provider, "sent_at": now})
+    updated_count = Notification.query().filter(
+        Notification.reference.in_(references)
+    ).update(
+        update_dict
+    )
 
-    db.session.query(
-        NotificationHistory).filter(NotificationHistory.job_id == job_id).update(
-        {'status': NOTIFICATION_SENDING, "sent_by": provider, "sent_at": now, "updated_at": now})
+    NotificationHistory.query().filter(
+        NotificationHistory.reference.in_(references)
+    ).update(
+        update_dict
+    )
 
     return updated_count