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 f7e31c0a)

Change-Id: Ib2f70696d98c6e1500d1d419d6acf0a8d0487213