Merge "Default to using SplitSelectSource drawable if TaskView icon drawable is null" into tm-qpr-dev am: 8e307ba50a am: 3e5b212204

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/22347415

Change-Id: I2f3da1c74ed5ae04ff9cbc4bc06e280da5390b4d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>