Prioritize System shortcuts over shortcut services

Shortcut services is legacy way to define shortcuts in different
components. We should migrate shortcut services to KeyGestureHandler
APIs. But as a stop gap reduce priority of shortcut services so
they don't block system shortcuts.

Currently only 2 shortcuts are registered through shortcut services,
and they apparently do nothing.

Test: manual
Bug: 358569822
Flag: EXEMPT bugfix
Change-Id: I9c0fbcacd1b2a020178f65ad0e39c0f96a1bdd05