Issue #3435918 use _GITLAB_TEMPLATES_REF

Closes #3435918

.gitlab-ci.yml

@@ -39,7 +39,7 @@ include:
     # - Minor or Major latests - `ref: 1.x-latest` or `ref: 1.0.x-latest` - Get the latest additions within a minor (mostly bugfixes) or major (bugs and new features).
     # - Fixed tag - `ref: 1.0.1` - Set the value to a known tag. This will not get any updates.
     # If you change the default value of ref, you should set the _CURL_TEMPLATES_REF variable in the variables section to be the same as set here.
-    ref: main
+    ref: $_GITLAB_TEMPLATES_REF
     file:
       - '/includes/include.drupalci.main.yml'
       # EXPERIMENTAL: For Drupal 7, remove the above line and uncomment the below.