Merge "Null out Activity in split controller" into udc-qpr-dev am: 09892161

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/24503472



Change-Id: Icb070c092a4097015a20eabaa7d755f7f2e157bc
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>