Test harness setting shouldn't prevent verification.

Doing so prevents us running GTS tests of the package verifier. Test
harnesses can achieve the same effect in a less irreversible way using
PACKAGE_VERIFIER_INCLUDE_ADB, and as far as I can tell they already do
so.

Note also that isRunningInTestHarness() is deprecated.

Test: atest PackageVerifierTest
Test: Verified tests pass even if ro.test_harness is set to 1
Bug: 137937263
Bug: 135751498
Bug: 7233608
Change-Id: I3b7966b4a26055b2a9fbd02d6e307c7fc7bf22f6