[2138] removed "statistics-iterval" configration from system tests

tests/system/bindctl/nsx1/b10-config.db.template.in

@@ -2,7 +2,6 @@
  "Auth": {
    "listen_on": [{"address": "10.53.0.1", "port": 53210}],
    "database_file": "@abs_builddir@/zone.sqlite3",
-   "statistics-interval": 1
  },
  "data_sources": {
     "classes": {

tests/system/bindctl/tests.sh

@@ -52,7 +52,6 @@ n=`expr $n + 1`
 
 echo "I:Checking BIND 10 statistics after a pause ($n)"
 # wait for 2sec to make sure b10-stats gets the latest statistics.
-# note that we set statistics-interval to 1.
 sleep 2
 echo 'Stats show
 ' | $RUN_BINDCTL \