Do not allow non-system apps to provide unverified attributions am: ec8a2057 am: b5e0dc4b

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/31451895



Change-Id: I5f3bd1d213613f932e5a91a2989547143a1acbe5
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>