Enable proxy for prometheus in devops portal

This patch required for enabling heatmap in DOP

Change-Id: I52c333d7a70b798f7e518c8c3934568cde0b77bf
diff --git a/devops_portal/service/stacklight-prometheus.yml b/devops_portal/service/stacklight-prometheus.yml
index 119c13f..9b5a74f 100644
--- a/devops_portal/service/stacklight-prometheus.yml
+++ b/devops_portal/service/stacklight-prometheus.yml
@@ -6,7 +6,7 @@
     config:
       service:
         stacklight-prometheus:
-          configure_proxy: false
+          configure_proxy: true
           enabled: true
           endpoint:
             address: ${_param:grafana_prometheus_address}