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

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



Change-Id: I917fbefa7ecd6ef2fdbf8e7610569fcdf5c04a95
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>