PackageManager: Clean up code related to foreign dex use

We simplified the way we track whether or not a dex file is used by
other apps. DexManager in the framework keeps track of the data and we
no longer need file markers on disk.

Test: device boots, foreign dex markers are not created anymore

Bug: 32871170

(cherry picked from commit 74f0a345)

Change-Id: I2a9daca15e5120518852584fa17aa94012af8f1a
Merged-In: I3660e2f3913a73904181449c2d910af0a0477950