test: avoid empty fixture in fs test

Refactor test-fs-error-messages to use tmpdir for its empty directory
rather than using a not-actually-empty directory called "empty" in
fixtures.

PR-URL: #21044
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

test/parallel/test-fs-error-messages.js

@@ -22,13 +22,17 @@
 'use strict';
 const common = require('../common');
 const fixtures = require('../common/fixtures');
+const tmpdir = require('../common/tmpdir');
 const assert = require('assert');
 const fs = require('fs');
+
+tmpdir.refresh();
+
 const nonexistentFile = fixtures.path('non-existent');
 const nonexistentDir = fixtures.path('non-existent', 'foo', 'bar');
 const existingFile = fixtures.path('exit.js');
 const existingFile2 = fixtures.path('create-file.js');
-const existingDir = fixtures.path('empty');
+const existingDir = tmpdir.path;
 const existingDir2 = fixtures.path('keys');
 const { COPYFILE_EXCL } = fs.constants;
 const uv = process.binding('uv');