Call the Drupal scaffold callback for create project events only

src/Plugin.php

@@ -50,13 +50,29 @@ class Plugin extends BasePlugin {
    */
   public static function getSubscribedEvents(): array {
     return [
-      ScriptEvents::POST_CREATE_PROJECT_CMD => 'prepareProject',
+      ScriptEvents::POST_CREATE_PROJECT_CMD => 'createProject',
       ScriptEvents::POST_UPDATE_CMD => 'prepareProject',
     ];
   }
 
   /**
-   * Post create and update project event callback.
+   * Post create project event callback.
+   *
+   * @param \Composer\Script\Event $event
+   *   The event that triggered the plugin.
+   *
+   * @throws \Twig_Error_Loader
+   * @throws \Twig_Error_Runtime
+   * @throws \Twig_Error_Syntax
+   */
+  public function createProject(Event $event) {
+    $this->scaffoldHandler->downloadScaffold();
+    $this->scaffoldHandler->generateAutoload();
+    $this->prepareProject($event);
+  }
+
+  /**
+   * Post update project event callback.
    *
    * @param \Composer\Script\Event $event
    *   The event that triggered the plugin.