Merge "Remove deprecated BOARD_BUILD_SYSTEM_ROOT_IMAGE" am: 9b123de886

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2239484

Change-Id: Ib51581201b07458897f2fe34a40644ea402dbef3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>