Revert "Allow debugging."

This reverts commit e9cbf6e5.

resources/runner/drupal.yml

@@ -208,7 +208,7 @@ drupal:
         ];
         // Location of the site configuration files.
         $settings['config_sync_directory'] = '../config/sync';
-        $settings['config_readonly'] = FALSE; // !file_exists(getcwd() . '/../disable-config-readonly');
+        $settings['config_readonly'] = !file_exists(getcwd() . '/../disable-config-readonly');
       Testing configuration alters: |
         // The video from the home page interacts with Selenium tests.
         $config['page_manager.page_variant.homepage-layout_builder-0']['variant_settings']['sections'][4]['components']['6ab0ceea-4541-4153-8b64-227e02369d30']['configuration']['text'] = 'Some joinup video';