Previously, dnsrps test was executed as an optional part of the rpz and
rpzrecurse system tests. This was conceptually problematic, as the test
took the responsibility of running parts of the test framework -
cleaning files and setting up servers again.
Instead, allow these tests to execute either the native variant, or the
dnsrps one. To ensure the same test coverage, trigger both of these
variants as separate test cases from pytest.
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