Add new upforwd system test

Add a new upforwd system test that checks if update forwarding still
works if the first primary is badly configured.

We cannot reuse the 'example.' zone for this test because that
checks if update forwarding works for DoT. What transport is used
in the new test is of no relevance.

Update the system test to use different known good file names for
the different zones that are being tested.

bin/tests/system/upforwd/ns1/example3.db

@@ -0,0 +1,18 @@
+; Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+;
+; SPDX-License-Identifier: MPL-2.0
+;
+; This Source Code Form is subject to the terms of the Mozilla Public
+; License, v. 2.0.  If a copy of the MPL was not distributed with this
+; file, you can obtain one at https://mozilla.org/MPL/2.0/.
+;
+; See the COPYRIGHT file distributed with this work for additional
+; information regarding copyright ownership.
+
+@	3600	SOA	n1.example3. hostmaster.ns1.example3. (
+			1 3600 1200 604800 7200 )
+		NS	ns2.example3.
+		NS	ns3.example3.
+ns1		A	10.53.0.1
+ns2		A	10.53.0.2
+ns3		A	10.53.0.3