Replace package variant specific APK keys with a single one.

Simpler, and necessary to align with the release and dev keys.

Test: Build & boot
Bug: 135753770
Change-Id: If4d73075c9516244acc687858934b3f976e661f8
Merged-In: If4d73075c9516244acc687858934b3f976e661f8
9 files changed