Merge "Animate clear all button's alpha after last task has scrolled beyond its edge." into tm-dev am: 08a408408c am: b2c3d4f58b

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

Change-Id: I9742f559d2a35adf0bb468d58139e18a886dc00b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>