"wildcard" system test: make root hints consistent with authoritative data

Multiple resolvers in the "wildcard" system test are configured with a single root hint: "ns.root-servers.nil", pointing to 10.53.0.1, which is inconsistent with authoritative data served by ns1. This may cause intermittent resolution failures, triggering false positives for the "wildcard" system test. Prevent this from happening by making ns2, ns3, and ns5 use root hints corresponding to the contents of ns1/root.db.in.