Use PackageManager query instead of permissions review mode booleans.

There are currently two configuration booleans for permissions review
mode: (1) a Build flag, and (2) a system config boolean. ag/1835531
added a query to PackageManager to hide these, so this CL changes the
usages within PackageInstaller to use this query instead of the booleans
directly.

BUG: 35028846
TEST: Run permissions CTS tests on Nexus 6.
Change-Id: I84516ba39be0de2bfdc953670dc54d5bd761b3a5