The race is between `NotificationTimerHandler`, which sends a reminder notification
after a certain inverval during problem states and `SendNotificationsHandler` which
sends out the notifications on state changes.
When the timer handler runs just before a state change triggers a notification, the
timer handler might pick up that state-change before the send notification handler
can set its no_more_notifications flag. In that case a "reminder" notification will
be sent out before the initial one, and despite `interval = 0` on the notification
object.
This includes a few common scenarios and a reproduction of the current behavior
affected by the underlying bug of issue #10575. This is done both to document
the change in behavior, as well as to ensure the behavior of the other scenarios
stays the same before and after the fix is applied.