test: ignore helper files in WPTs

PR-URL: #48079
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Matthew Aitken <maitken033380023@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

test/common/wpt.js

@@ -368,7 +368,7 @@ class StatusLoader {
         const list = this.grep(filepath);
         result = result.concat(list);
       } else {
-        if (!(/\.\w+\.js$/.test(filepath))) {
+        if (!(/\.\w+\.js$/.test(filepath)) || filepath.endsWith('.helper.js')) {
           continue;
         }
         result.push(filepath);