Added gainsight_elasticsearch related files

The new Stacklight related dockerized service: gainsight_elasticsearch.

Change-Id: I206e5252f2a9a238686f0380a42d302710b28d51
Related-Bug: PROD-25532
diff --git a/prometheus/gainsight/elasticsearch_container.yml b/prometheus/gainsight/elasticsearch_container.yml
new file mode 100644
index 0000000..8a10fbf
--- /dev/null
+++ b/prometheus/gainsight/elasticsearch_container.yml
@@ -0,0 +1,3 @@
+classes:
+- service.prometheus.gainsight.elasticsearch_container
+