Draft: iter_pcnamech.rpl: fix overlapping ranges

Blocked by knot-resolver#658.

Previously, the scenario tested NOTHING.

So after the fix, it requires resolver to do parent-side query to get an extra NS name which is needed in order to pass.

Knot Resolver is currently pretty parent centric, so fixed scenario will fail. Let's reintroduce it (or not) once we solve the parent/child problem for good.