Delete old forward-locked apps on upgrade

The old style forward-locked apps were in a directory called
/data/app-private but the new style forward-locked apps are in ASEC
containers. This made the upgrade path confused and it wouldn't
correctly generate the InstallArgs to delete the old file.

Bug: 6619438
Change-Id: If4323fa8701d9fc653998f5db58670b4124b9e87