[RESTRICT AUTOMERGE][pm] prevent system app downgrades of versions lower than preload am: aec76152

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/21162033



Change-Id: Ifb5c92fcd4846457a950bc46cc3183e1a418ae3d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>