UX polish for the quick affordance picker. am: d6772973e0

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/20946745

Change-Id: Ia7e9ca8be16aacd96ce2020756220024db498483
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>