[RESTRICT AUTOMERGE][pm] still allow debuggable for system app downgrades am: 3a04799f

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/21266934



Change-Id: I8b05bb505c5ad65d4b8ba4b41ecc9810d2f18ac9
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>