Merge "Wait for shell drop target to be ready for handling drags in tests" into udc-dev am: 52cc03e42c am: d03767df3d am: f55cbe1374

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/22935091

Change-Id: Ie11ac0b53966082073ee60d43fa7bba99acc241a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>