Before this commit, events were sorted by ID in month view.
Event A occurring after event B would be placed on top of B instead
of below.

Steps to reproduce:

* Go in the calendar app
* Insert a event at 12:00
* Insert a event at 8:00
* Insert a event at 14:00
* Go in view month the events are not sorted (BUG)

In month view, events are forced to be "allday", so the sequence used
can't be based on its time but only on its ID.

To fix this, this commit doesn't force the "allday" flag anymore.

Task ID: 2183249