[2136] set "poll-interval" to one second for system test

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

@@ -3,5 +3,8 @@
    "listen_on": [{"address": "10.53.0.1", "port": 53210}],
    "database_file": "@abs_builddir@/zone.sqlite3",
    "statistics-interval": 1
+ },
+ "Stats": {
+   "poll-interval": 1
  }
 }