Use 'openstack' in Grafana dashboard tags

Change-Id: Ie806ddd4756a80e5b18b448b28cf036d6bf06f49
Related-Bug: PROD-17781
diff --git a/heat/files/grafana_dashboards/heat_prometheus.json b/heat/files/grafana_dashboards/heat_prometheus.json
index b63b993..3c09680 100644
--- a/heat/files/grafana_dashboards/heat_prometheus.json
+++ b/heat/files/grafana_dashboards/heat_prometheus.json
@@ -510,7 +510,9 @@
   ],
   "schemaVersion": 14,
   "style": "dark",
-  "tags": [],
+  "tags": [
+    "openstack"
+  ],
   "templating": {
     "list": [
       {
diff --git a/heat/files/grafana_dashboards/heat_prometheus_fluentd.json b/heat/files/grafana_dashboards/heat_prometheus_fluentd.json
index 0605817..d27bf3c 100644
--- a/heat/files/grafana_dashboards/heat_prometheus_fluentd.json
+++ b/heat/files/grafana_dashboards/heat_prometheus_fluentd.json
@@ -510,7 +510,9 @@
   ],
   "schemaVersion": 14,
   "style": "dark",
-  "tags": [],
+  "tags": [
+    "openstack"
+  ],
   "templating": {
     "list": [
       {