Enable {%raw%} in grafana dashboard template

Change-Id: Iff39e2a916bc320a498568d3f4f02f2a83d03227
diff --git a/prometheus/files/grafana_dashboards/prometheus_performances_prometheus.json b/prometheus/files/grafana_dashboards/prometheus_performances_prometheus.json
index 307efa1..0ff1031 100644
--- a/prometheus/files/grafana_dashboards/prometheus_performances_prometheus.json
+++ b/prometheus/files/grafana_dashboards/prometheus_performances_prometheus.json
@@ -1,3 +1,4 @@
+{% raw %}
 {
   "annotations": {
     "list": []
@@ -1708,3 +1709,4 @@
   "title": "Prometheus Performances",
   "version": 4
 }
+{% endraw %}