Add authentication preparation to private modules test template

private-modules.yml

 include:
+  - project: gitlab-ci-cd/general
+    ref: main
+    file: '/mixins.yml'
   - project: 'gitlab-ci-cd/composer-packages'
     ref: main
     file: '/composer-packages.yml'
@@ -15,6 +18,7 @@ stages:
 default:
   tags:
     - default
+  before_script: !reference [.prepareaccess, before_script]
 
 workflow:
   rules: