Remove the toolbar controller's own event system

The toolbar controller has an own event system which is complex, extremely slow
and not used. For me, this change reduces loading time of the Italy item from
~170s to ~18s.

Also, there were several bugs in this implementation. Event handlers were called
multiple times and the filtering on selector did not work at all.

Bug: 61850
Change-Id: Idb6432e6857069058d4e6fe519ebbc31c883acf2