Fix crash/flicker with taskbar when canceling drag and drop am: 729eb845

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/17776925



Change-Id: I4aaa28e1aa1a097b1484cc3c18d572e7f94c78e7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>