Issue #3239466: Refactor build tests to use core-supported project templates

tests/src/Build/CoreUpdateTest.php

@@ -113,6 +113,13 @@ class CoreUpdateTest extends UpdateTestBase {
     $core_constraint = preg_replace('/\.[0-9]+-dev$/', '.x-dev', \Drupal::VERSION);
     // Require the current version of core, to install its dependencies.
     $data['require']['drupal/core'] = $core_constraint;
+    unset($data['require']['drupal/core-recommended']);
+    // Until we officially support updating these plugins, allow them to be
+    // installed in any version.
+    // @see https://www.drupal.org/project/automatic_updates/issues/3233138
+    $data['require']['drupal/core-vendor-hardening'] = '*';
+    $data['require']['drupal/core-project-message'] = '*';
+    $data['require']['drupal/core-composer-scaffold'] = '*';
 
     return $data;
   }