Remove alert for email / sms in created

In response to [1].

[1]: https://github.com/alphagov/notifications-api/pull/3383#discussion_r759379988

It turns out the code that inspired this new alert - in the old
"timeout-sending-notifications" task - was actually redundant as
we already have a task to "replay" notifications still in "created",
which is much better than just alerting about them.

It's possible the replayed notifications will also fail, but in
both cases we should see some kind of error due to this, so I don't
think we're losing anything by not having an alert.

app/dao/notifications_dao.py

@@ -487,16 +487,6 @@ def dao_delete_notifications_by_id(notification_id):
     ).delete(synchronize_session='fetch')
 
 
-def dao_check_notifications_still_in_created(minimum_age_in_seconds):
-    min_created_at = datetime.utcnow() - timedelta(seconds=minimum_age_in_seconds)
-
-    return Notification.query.filter(
-        Notification.created_at < min_created_at,
-        Notification.status == NOTIFICATION_CREATED,
-        Notification.notification_type.in_([SMS_TYPE, EMAIL_TYPE])
-    ).count()
-
-
 def dao_timeout_notifications(timeout_period_in_seconds):
     """
     Timeout SMS and email notifications by the following rules: