Change app code path

Incremental (go/incremental-apk) requires bind-mounting on /data/app/...
directories. The purpose of this change is to avoid leaking package names in
/proc/mounts.

Default apk path of an installed app:
Before: /data/app/[packageName]-[randomString]/base.apk
After: /data/app/~~[randomStringA]/[packageName]-[randomStringB]/base.apk

BUG: b/147371381 b/148237378
Test: manual
Change-Id: Ib05b187dc006272603709a95534c40744cd62f0c