Move from latest tags to nightly for SLv2 images

Related-PROD: PROD-20223

Change-Id: I4510c8d59e6a1e77a31965cc588ba039846e3b04
diff --git a/classes/cluster/virtual-mcp-pike-dvr-ceph-rgw/stacklight/server.yml b/classes/cluster/virtual-mcp-pike-dvr-ceph-rgw/stacklight/server.yml
index 9a02cdc..17f0c74 100644
--- a/classes/cluster/virtual-mcp-pike-dvr-ceph-rgw/stacklight/server.yml
+++ b/classes/cluster/virtual-mcp-pike-dvr-ceph-rgw/stacklight/server.yml
@@ -52,7 +52,7 @@
     docker_image_remote_storage_adapter: docker-prod-local.artifactory.mirantis.com/openstack-docker/remote_storage_adapter:${_param:apt_mk_version}
     docker_image_remote_collector: docker-prod-local.artifactory.mirantis.com/openstack-docker/heka:${_param:apt_mk_version}
     docker_image_prometheus_relay: docker-prod-local.artifactory.mirantis.com/openstack-docker/prometheus_relay:${_param:apt_mk_version}
-    docker_image_grafana: grafana/grafana:5.1.3
+    docker_image_grafana: docker-prod-local.artifactory.mirantis.com/mirantis/external/grafana:${_param:apt_mk_version}
     influxdb_port: 8086
     influxdb_admin_password: password
     influxdb_stacklight_password: lmapass