Refactor runtime hidden API flag from negative to positive

There are only two situations in which we want to enable hidden API
access flag checks. Turning the flag from DISABLE_ to ENABLE_
simplifies logic in ART and reduces the number places where the flag
had to be passed down to ART.

Bug: 64382372
Test: boot device, install and run apps, check log messages
(cherry picked from commit 22cce5a1)

Change-Id: I468df458e9dd9e6a9b5ec56c03d1ba56c850c4dc