Move PackageManagerTests to postsubmit am: 7a350b8d14

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/24454171

Change-Id: Ifcc556246fc8855f9c72d8050f2a09614ad8dedd
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>