Remove A11y feature dependent shortcuts from blocklisted triggers

A11y services have access to key events through input filter which
is earlier in input pipeline than KGC shortcut handling. So, we
don't need to reserve these shortcuts. This allows users to set
these key combinations as custom shortcuts.
Since, most users wont have A11y services like magnification,
talkback, etc enabled, it makes sense to have these combinations
available for custom shortcuts (discussed with A11y PM and UX).

Test: atest InputTests
Bug: 398195149
Flag: EXEMPT bugfix
Change-Id: Ia7c1085a4d2d28687c2187f3bc7eb10c75f89e63