Make root hints consistent with authoritative data

Resolvers in the "filter-aaaa" system test are configured with a single
root hint: "ns.rootservers.net", pointing to 10.53.0.1.  However,
querying ns1 for "ns.rootservers.net" results in NXDOMAIN answers.
Since the TTL for the root hint is set to 0, it may happen that a
resolver's ADB will be asked to return any known addresses for
"ns.rootservers.net", but it will only have access to a cached NXDOMAIN
answer for that name and an expired root hint, which will result in a
resolution failure, triggering a false positive for the "filter-aaaa"
system test.  Prevent this from happening by making all the root hints
consistent with authoritative data served by ns1.

(cherry picked from commit c19ebde14b)

bin/tests/system/filter-aaaa/ns2/hints

@@ -7,5 +7,8 @@
 ; See the COPYRIGHT file distributed with this work for additional
 ; information regarding copyright ownership.
 
-. 0 NS ns.rootservers.utld.
-ns.rootservers.utld. 0 A 10.53.0.1
+$TTL 120
+
+.		NS	ns.utld.
+ns.utld.	A	10.53.0.1
+ns.utld.	AAAA	fd92:7065:b8e:ffff::1

bin/tests/system/filter-aaaa/ns3/hints

@@ -7,5 +7,8 @@
 ; See the COPYRIGHT file distributed with this work for additional
 ; information regarding copyright ownership.
 
-. 0 NS ns.rootservers.utld.
-ns.rootservers.utld. 0 A 10.53.0.1
+$TTL 120
+
+.		NS	ns.utld.
+ns.utld.	A	10.53.0.1
+ns.utld.	AAAA	fd92:7065:b8e:ffff::1

bin/tests/system/filter-aaaa/ns5/hints

@@ -7,5 +7,8 @@
 ; See the COPYRIGHT file distributed with this work for additional
 ; information regarding copyright ownership.
 
-. 0 NS ns.rootservers.utld.
-ns.rootservers.utld. 0 A 10.53.0.1
+$TTL 120
+
+.		NS	ns.utld.
+ns.utld.	A	10.53.0.1
+ns.utld.	AAAA	fd92:7065:b8e:ffff::1