Use hasSystemFeature(String) overload for RoSystemFeatures fallback

Prefer the simpler overload when falling back to runtime queries. This
has identical semantics to hasSystemFeature(String, 0), but avoids the
need to update any/all mocked overrides that reference the simpler (and
more common) overload. There should be no functional impact otherwise.

Bug: 203143243
Flag: EXEMPT refactor
Test: atest systemfeatures-gen-golden-tests systemfeatures-gen-tests
Change-Id: I7a527663c677000f49426c6df02875e63a928e09