Remove unused listener

 - Remove OnMainSwitchChangeListener and it's interface since the
   callback will duplicate with setCheck() method, cause the toggle on
   event come with twice while on and off, in futher to casue some
   duplicate work or error metrics logging

Bug: 218405966
Test: make SettingsRoboTests
Change-Id: If20ed6488d21443b9c623e8fe4de383a84ea673a