remove duplication shutdown loggers

also add **kwargs to make it celery4 compatible

app/celery/tasks.py

@@ -2,9 +2,7 @@ import json
 from datetime import datetime
 from collections import namedtuple, defaultdict
 
-from celery.signals import worker_process_shutdown
 from flask import current_app
-
 from notifications_utils.recipients import (
     RecipientCSV
 )
@@ -74,11 +72,6 @@ from app.service.utils import service_allowed_to_send_to
 from app.utils import convert_utc_to_bst
 
 
-@worker_process_shutdown.connect
-def worker_process_shutdown(sender, signal, pid, exitcode):
-    current_app.logger.info('Tasks worker shutdown: PID: {} Exitcode: {}'.format(pid, exitcode))
-
-
 @notify_celery.task(name="process-job")
 @statsd(namespace="tasks")
 def process_job(job_id):