Merge "Disallow system apps to be installed/updated as instant." into rvc-dev am: 35b1a471

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/25716297



Change-Id: Iee38deb0acdbe5ecd5af974c7c0709d8c53054f2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>