Use removePackageLI instead of removing mPackages

When adding an system app via OTA, trying to remove it from mPackages
directly doesn't work. The ContentProviders and other things aren't
removed and point to the hidden system app's applicationInfo instead of
the updated app.

Bug: 6685263
Change-Id: I487cf518e0e3c60fae736e9b974617023a7dee8d