fs: remove experimental warning for fs.promises

This has been warning for long enough, without any API changes
in the last few months.

PR-URL: https://github.com/nodejs/node/pull/26581
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/fs.md

@@ -3699,7 +3699,7 @@ this API: [`fs.write(fd, string...)`][].
 
 ## fs Promises API
 
-> Stability: 1 - Experimental
+> Stability: 2 - Stable
 
 The `fs.promises` API provides an alternative set of asynchronous file system
 methods that return `Promise` objects rather than using callbacks. The

lib/fs.js

@@ -1930,13 +1930,10 @@ Object.defineProperties(fs, {
   },
   promises: {
     configurable: true,
-    enumerable: false,
+    enumerable: true,
     get() {
-      if (promises === null) {
+      if (promises === null)
         promises = require('internal/fs/promises');
-        process.emitWarning('The fs.promises API is experimental',
-                            'ExperimentalWarning');
-      }
       return promises;
     }
   }

test/parallel/test-fs-promises.js

@@ -40,9 +40,8 @@ function nextdir() {
   return `test${++dirc}`;
 }
 
-// fs.promises should not be enumerable as long as it causes a warning to be
-// emitted.
-assert.strictEqual(Object.keys(fs).includes('promises'), false);
+// fs.promises should not enumerable.
+assert.strictEqual(Object.keys(fs).includes('promises'), true);
 
 {
   access(__filename, 'r')