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/rpzrecurse/ns2/named.default.conf

@@ -17,4 +17,7 @@ view "recursive" {
 	type hint;
 	file "root.hint";
     };
+
+    recursion yes;
+    dnssec-validation yes;
 };