remove jobs from letter api calls

we now no longer create a job. At the end of the post there is no
action, as we don't have any tasks to queue immediately - if it's a
real notification it'll get picked up in the evening scheduled task.

If it's a test notification, we create it with an initial status of
sending so that we can be sure it'll never get picked up - and then we
trigger the update-letter-notifications-to-sent-to-dvla task to sent
the sent-at/by.

app/celery/scheduled_tasks.py

@@ -335,17 +335,17 @@ def run_letter_notifications():
     if notifications:
         file_contents = create_dvla_file_contents_for_notifications(notifications)
 
-        file_location = '{}-dvla-notifications.txt'.format(current_time)
+        filename = '{}-dvla-notifications.txt'.format(current_time)
         s3upload(
             filedata=file_contents + '\n',
             region=current_app.config['AWS_REGION'],
             bucket_name=current_app.config['DVLA_BUCKETS']['notification'],
-            file_location=file_location
+            file_location=filename
         )
 
         notify_celery.send_task(
             name=TaskNames.DVLA_NOTIFICATIONS,
-            kwargs={'filename': file_location},
+            kwargs={'filename': filename},
             queue=QueueNames.PROCESS_FTP
         )
         current_app.logger.info(

app/celery/tasks.py

@@ -46,7 +46,10 @@ from app.models import (
     JOB_STATUS_IN_PROGRESS,
     JOB_STATUS_FINISHED,
     JOB_STATUS_READY_TO_SEND,
-    JOB_STATUS_SENT_TO_DVLA, JOB_STATUS_ERROR)
+    JOB_STATUS_SENT_TO_DVLA, JOB_STATUS_ERROR,
+    NOTIFICATION_SENDING,
+    NOTIFICATION_TECHNICAL_FAILURE
+)
 from app.notifications.process_notifications import persist_notification
 from app.service.utils import service_allowed_to_send_to
 from app.statsd_decorators import statsd
@@ -343,7 +346,6 @@ def update_letter_notifications_to_sent_to_dvla(self, notification_references):
 @statsd(namespace="tasks")
 def update_letter_notifications_to_error(self, notification_references):
     # This task will be called by the FTP app to update notifications as sent to DVLA
-    provider = get_current_provider(LETTER_TYPE)
 
     updated_count = dao_update_notifications_by_reference(
         notification_references,