Unregister listeners from ClockRegistry when destroyed am: e980bd3a5d am: 36c82537a1 am: 3c3c285fbb am: 9fda58a2d4

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/23407197

Change-Id: Ic7463c9803740fd1818c517285591173dabb2287
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>