Revert "Revert "Merge "Restore V2+ signature requirement for system apps" into...

Revert "Revert "Merge "Restore V2+ signature requirement for system apps" into tm-dev am: a347b6c2 am: 8aa6d201""

This reverts commit b07fdf9c.

Reason for revert: Both b/230910314 and b/231165527 have been resolved with the updated APKs in the system image. tm-dev is still enforcing the V2+ signature requirement for system apps; this revert restores this requirement for Pixel devices.

Bug: 215046612
Bug: 230910314
Bug: 231165527
Change-Id: I801b14b1031c44fdd34d53450bddf56f437b1fbe