[pm] fix dynamic library after update and restart

There was a mistake in the refactoring CL ag/20136647 where the wrong
disabledPs was used. This CL fixes that.

Test: manual with the following steps:

1. adb pull /product/priv-app/PrebuiltGmsCore/PrebuiltGmsCoreNext.apk
2. adb install PrebuiltGmsCoreNext.apk // this step simulates installing
   a system app update on the /data partition
3. reboot and check the Libraries section in dumpsys. Make sure that
   gmscore still shows up there

BUG: 310550085

Change-Id: I9e1f7d672674ea7e0707dba65f18f041edf4ff83