Update expected code for http_response

Change-Id: I9cd6653a0ad56cb6b00d0b9efa564a39408339c7
diff --git a/nova/meta/telegraf.yml b/nova/meta/telegraf.yml
index af428a6..bda7082 100644
--- a/nova/meta/telegraf.yml
+++ b/nova/meta/telegraf.yml
@@ -11,4 +11,5 @@
     http_response:
       nova-api:
         address: "http://{{ controller.bind.private_address|replace('0.0.0.0', '127.0.0.1') }}:8774/"
+        expected_code: 200
 {%- endif %}