Update gitlab-ci for Elasticsearch 5.1

.gitlab-ci.yml

@@ -9,7 +9,7 @@ variables:
   MYSQL_ALLOW_EMPTY_PASSWORD: "1"
   # retry tests only in CI environment
   RSPEC_RETRY_RETRY_COUNT: "3"
-  ELASTIC_HOST: "registry.gitlab.com-gitlab-org-test-elastic-image"
+  ELASTIC_HOST: "elasticsearch"
   RAILS_ENV: "test"
   SIMPLECOV: "true"
   SETUP_DB: "true"
@@ -55,7 +55,7 @@ stages:
   services:
     - mysql:latest
     - redis:alpine
-    - registry.gitlab.com/gitlab-org/test-elastic-image
+    - elasticsearch:5.1
 
 .rspec-knapsack: &rspec-knapsack
   stage: test