Remove instant apps access to verifier consent setting.

This setting should be private to GPP, and there should be no reason
for any app to access it.  And GPP is migrating away from this
relatively public setting, so it can't be relied upon.

Test: Builds
Bug: 135751498
Bug: 37119785
Change-Id: I839c2d67ae54b4df184ea7ee1c7aebee72c6e794