Notif handlers:remove double check of event type

Change Id50a4a42a8dddbffb85b5fbca43f1b7f31447874 made the
call to handler's process_notification to happen only on registered
event types. There's not need to check the event type inside the
handler itself.

Also remove the unit test because the part of the code that is
tested is never executed.

Change-Id: I75e204d5ff44d3dd0100393a98cc2537886eaa05
Merge "Notif handlers:remove double check of event type"