Remove the use of schedule_for in post_notifications.

Years ago we started to implement a way to schedule a notification. We hit a problem but we never came up with a good solution and the feature never made it back to the top of the priority list.

This PR removes the code for scheduled_for. There will be another PR to drop the scheduled_notifications table and remove the schedule_notifications service permission

Unfortunately, I don't think we can remove the `scheduled_for` attribute from the notification.serialized method because out clients might fail if something is missing. For now I have left it in but defaulted the value to None.

tests/app/db.py

@@ -10,7 +10,6 @@ from app.dao.invited_user_dao import save_invited_user
 from app.dao.jobs_dao import dao_create_job
 from app.dao.notifications_dao import (
     dao_create_notification,
-    dao_created_scheduled_notification
 )
 from app.dao.organisation_dao import dao_create_organisation, dao_add_service_to_organisation
 from app.dao.permissions_dao import permission_dao
@@ -39,7 +38,6 @@ from app.models import (
     ServiceInboundApi,
     ServiceCallbackApi,
     ServiceLetterContact,
-    ScheduledNotification,
     ServicePermission,
     ServiceSmsSender,
     ServiceWhitelist,
@@ -294,14 +292,6 @@ def create_notification(
     }
     notification = Notification(**data)
     dao_create_notification(notification)
-    if scheduled_for:
-        scheduled_notification = ScheduledNotification(id=uuid.uuid4(),
-                                                       notification_id=notification.id,
-                                                       scheduled_for=datetime.strptime(scheduled_for,
-                                                                                       "%Y-%m-%d %H:%M"))
-        if status != 'created':
-            scheduled_notification.pending = False
-        dao_created_scheduled_notification(scheduled_notification)
 
     return notification