Fix face unlock confirmation button behavior to respect "always
require confirmation" setting. Adjust the description of the
confirmation toggle in private space face unlock settings to
reflect this change.
Screenshot: https://screenshot.googleplex.com/4uHfm9Z3ZE56ZaT.png
Bug: 342383195
Test: Tested manually by flashing local build
Change-Id: I0f742839a862fe66cacad9f5704dbe8b0df3a0c2