Merge "Removing BOARD_BUILD_SYSTEM_ROOT_IMAGE" am: 239ab9e265 am: cafddba4e8 am: 78b7d28908

Original change: https://android-review.googlesource.com/c/device/generic/common/+/2063543

Change-Id: Idca87c1090bab3a90fd539dfa6333724a9743a9c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>