Try curl with retry and reduce wait time to 30 sec

.gitlab-ci.yml

@@ -41,6 +41,6 @@ test:install:
     - support/set-gitlab-upstream
     - killall node
     - gdk run &
-    - sleep 240
-    - curl -f http://127.0.0.1:3000/
+    - sleep 30
+    - curl -f --retry 10 --retry-delay 5 http://127.0.0.1:3000/