Don't call into apexservice if device uses flattened apexes am: aedfef3c2f am: e0c1d5f924

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/1689748

Change-Id: I53f7d46da758e5cd337ced2ebe625e1de8ba5c2a