[RESTRICT AUTOMERGE][pm] prevent system app downgrades of versions lower than...

[RESTRICT AUTOMERGE][pm] prevent system app downgrades of versions lower than preload am: d7c72817

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/21159680



Change-Id: I69ea588e52956b1e08f5549000eb2b1907268ab6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>