Detect non-A/B vs. A/B packages correctly. am: 2a4afd29a1 am: 672fec0538 am: 1343db27c7

Original change: https://googleplex-android-review.googlesource.com/c/platform/bootable/recovery/+/11345696

Change-Id: Ia70db6c3fc68a5cda25007f2f2b2f0a45c02735a