Merge "Remove stage concept from split screen APIs" into tm-qpr-dev am: f876fb99 am: 945c1315

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/20112690



Change-Id: Ic958c606220e4b4e6650fefa2b1dc68b76d4beb1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>