test: remove --experimental-worker flag comment

worker is stable in the master branch. The flag is no longer required.

PR-URL: #31563
Reviewed-By: Richard Lau <[email protected]>
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Yongsheng Zhang <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Trivikram Kamat <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Rich Trott <[email protected]>

test/parallel/test-worker-fs-stat-watcher.js

@@ -1,4 +1,3 @@
-// Flags: --experimental-worker
 'use strict';
 const common = require('../common');
 const { Worker, parentPort } = require('worker_threads');