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

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

Change-Id: Ic7bf8ce725106c269b96cc6963cac22084898df9
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>