Added gainsight_elasticsearch related files

The new Stacklight related dockerized service: gainsight_elasticsearch.

Change-Id: I206e5252f2a9a238686f0380a42d302710b28d51
Related-Bug: PROD-25532
diff --git a/defaults/docker_images.yml b/defaults/docker_images.yml
index fa13bdf..f154381 100644
--- a/defaults/docker_images.yml
+++ b/defaults/docker_images.yml
@@ -29,6 +29,7 @@
     docker_image_grafana: "${_param:mcp_docker_registry}/openstack-docker/grafana:${_param:mcp_version}"
     docker_image_prometheus: "${_param:mcp_docker_registry}/openstack-docker/prometheus:${_param:mcp_version}"
     docker_image_prometheus_gainsight: "${_param:mcp_docker_registry}/openstack-docker/gainsight:${_param:mcp_version}"
+    docker_image_prometheus_gainsight_elasticsearch: "${_param:mcp_docker_registry}/openstack-docker/gainsight_elasticsearch:${_param:mcp_version}"
     docker_image_prometheus_relay: "${_param:mcp_docker_registry}/openstack-docker/prometheus_relay:${_param:mcp_version}"
     docker_image_pushgateway: "${_param:mcp_docker_registry}/openstack-docker/pushgateway:${_param:mcp_version}"
     docker_image_remote_agent: "${_param:mcp_docker_registry}/openstack-docker/telegraf:${_param:mcp_version}"