Bound drop target layout values to left and right. am: 3c0f4c15 am: 781c68b2

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/18491881



Change-Id: I14acd17e473d0f2a081a90e41bfb1598f21c49d9
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>