eliminate unnecessary waiting in allow-query test

- grep in the log to see if configuration is finished rather
  than sleeping for 5 seconds

bin/tests/system/allow-query/ns2/generic.db

@@ -0,0 +1,24 @@
+; Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+;
+; 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 http://mozilla.org/MPL/2.0/.
+;
+; See the COPYRIGHT file distributed with this work for additional
+; information regarding copyright ownership.
+
+$ORIGIN @
+$TTL 300	; 5 minutes
+@                       IN SOA	mname1. . (
+				1          ; serial
+				20         ; refresh (20 seconds)
+				20         ; retry (20 seconds)
+				1814400    ; expire (3 weeks)
+				3600       ; minimum (1 hour)
+				)
+			NS	ns2
+ns2			A	10.53.0.2
+			MX	10 mail
+
+a			A	10.0.7.1
+mail			A	10.0.7.2