Merge "Animate clear all button's alpha after last task has scrolled beyond its edge." into tm-dev am: 08a408408c

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/17319410

Change-Id: I9e0c88c8902022e2764d96911b6df58d818f56ca
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>