[GROOMING TASK][Notification component] Recheck how the "schedulingobjects" collection works

[itswillta]

There are currently 2 weird issues about the schedulingobjects collection that needs reviewing:

1. Deleting an event also creates a document in the schedulingobjects collection. So basically deleting an event creates a new event notification for the attendees. Therefore, an attendee can actually bring back the deleted/cancelled event by reacting (Yes/Maybe/No) to the event notification.
2. An attendee accepting/maybe-ing/declining an event also yields a new event notification for the organizer. I don't know if this is an expected behaviour.

So please recheck how new items (documents) are created in the schedulingobjects collection. After that, create an issue to fix the behaviours.