Merge "Restore V2+ signature requirement for system apps" into tm-dev am: a347b6c2 am: 8aa6d201

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/17416120



Change-Id: I4032d2148f13b4b1447a130ba9485345b68ef258
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>