test: replace forEach() with for...of

Replace `Array.prototype.forEach()` with `for...of` in
`parallel/test-whatwg-encoding-custom-textdecoder-utf16-surrogates.js`.

PR-URL: #50608
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-whatwg-encoding-custom-textdecoder-utf16-surrogates.js

@@ -43,7 +43,7 @@ const bad = [
   },
 ];
 
-bad.forEach((t) => {
+for (const t of bad) {
   assert.throws(
     () => {
       new TextDecoder(t.encoding, { fatal: true })
@@ -53,4 +53,4 @@ bad.forEach((t) => {
       name: 'TypeError'
     }
   );
-});
+}