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.

tests/app/celery/test_scheduled_tasks.py

@@ -19,7 +19,6 @@ from app.celery.scheduled_tasks import (
     check_job_status,
     delete_invitations,
     delete_verify_codes,
-    raise_alert_if_email_sms_still_in_created,
     remove_yesterdays_planned_tests_on_govuk_alerts,
     replay_created_notifications,
     run_scheduled_jobs,
@@ -109,24 +108,6 @@ def test_should_update_all_scheduled_jobs_and_put_on_queue(sample_template, mock
     ])
 
 
-def test_raise_alert_if_email_sms_still_in_created(notify_api, mocker):
-    mock_check = mocker.patch('app.celery.scheduled_tasks.dao_check_notifications_still_in_created')
-    mock_logger = mocker.patch('app.celery.scheduled_tasks.current_app.logger')
-
-    mock_check.return_value = 0
-    raise_alert_if_email_sms_still_in_created()
-    mock_logger.info.assert_called_once_with("0 notifications are still in 'created'.")
-
-    assert mock_check.called_once_with(
-        notify_api.config['CREATED_NOTIFICATIONS_ALERT_AGE']
-    )
-
-    # try again with something to alert about
-    mock_check.return_value = 1
-    raise_alert_if_email_sms_still_in_created()
-    mock_logger.error.assert_called_once_with("1 notifications are still in 'created'.")
-
-
 @freeze_time('2017-05-01 14:00:00')
 def test_switch_current_sms_provider_on_slow_delivery_switches_when_one_provider_is_slow(
     mocker,