use "primary" and "secondary" in statschannel output

zone statistics were still using the old terminology. NOTE: this
change may affect scripts that parse statistics output.

bin/tests/system/statistics/tests.sh

@@ -152,7 +152,7 @@ ret=0
 echo_i "checking that zones return their type ($n)"
 if $FEATURETEST --have-libxml2 && [ -x ${CURL} ] ; then
     ${CURL} http://10.53.0.1:${EXTRAPORT1}/xml/v3/zones > curl.out.${n} 2>/dev/null || ret=1
-    grep '<zone name="32/1.0.0.127-in-addr.example" rdataclass="IN"><type>master</type>' curl.out.${n} > /dev/null || ret=1
+    grep '<zone name="32/1.0.0.127-in-addr.example" rdataclass="IN"><type>primary</type>' curl.out.${n} > /dev/null || ret=1
 else
     echo_i "skipping test as libxml2 and/or curl was not found"
 fi