Merge "Removed onBackPressed handling in SplitSCreenSelectState" into sc-v2-dev am: e7e3d6ad31 am: 3c519248b6

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/16371718

Change-Id: Iebe599ce37b3d8f101fc14f284c4886d98d0ead7