update system tests so validation won't fail when using IANA key

- all tests with "recursion yes" now also specify "dnssec-validation yes",
  and all tests with "recursion no" also specify "dnssec-validation no".
  this must be maintained in all new tests, or else validation will fail
  when we use local root zones for testing.
- clean.sh has been modified where necessary to remove managed-keys.bind
  and viewname.mkeys files.

bin/tests/system/zero/clean.sh

@@ -15,3 +15,4 @@ rm -f ns4/example.bk
 rm -f dig.out*
 rm -f query.list
 rm -f ns*/named.lock
+rm -f ns*/managed-keys.bind*

bin/tests/system/zero/ns1/named.conf.in

@@ -18,6 +18,7 @@ options {
 	listen-on { 10.53.0.1; };
 	listen-on-v6 { none; };
 	recursion no;
+	dnssec-validation no;
 };
 
 zone "." {

bin/tests/system/zero/ns2/named.conf.in

@@ -18,6 +18,7 @@ options {
 	listen-on { 10.53.0.2; };
 	listen-on-v6 { none; };
 	recursion no;
+	dnssec-validation no;
 };
 
 zone "example" {

bin/tests/system/zero/ns3/named.conf.in

@@ -18,6 +18,7 @@ options {
 	listen-on { 10.53.0.3; };
 	listen-on-v6 { none; };
 	recursion yes;
+	dnssec-validation yes;
 };
 
 zone "." {

bin/tests/system/zero/ns4/named.conf.in

@@ -18,6 +18,7 @@ options {
 	listen-on { 10.53.0.4; };
 	listen-on-v6 { none; };
 	recursion no;
+	dnssec-validation yes;
 };
 
 zone "example" {