* Opacity preference will be disabled when fade is disabled
cherry picked from commit f9fdedaafe
Bug: 173940869
Test: atest AccessibilityButtonFadePreferenceControllerTest AccessibilityButtonOactiyPreferenceControllerTest
Change-Id: I1efd9760aa0287899cddd10ddd9a88a81ccc39ba
Merged-In: I1efd9760aa0287899cddd10ddd9a88a81ccc39ba