Remove selectability from pointer preferences.

Fix: 379840620
Fix: 374902522
Fix: 374902467
Fix: 374898232
Fix: 374894728
Fix: 374894804
Test: Manual. Talkback, switch access, voice access.
Flag: EXEMPT BugFix.
Change-Id: I550bd78893124b453d49f98d51dab2f49bee84f7