test: replace common.fixturesDir with fixtures

PR-URL: https://github.com/nodejs/node/pull/15845
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

test/parallel/test-fs-copyfile.js

@@ -1,9 +1,10 @@
 'use strict';
 const common = require('../common');
+const fixtures = require('../common/fixtures');
 const assert = require('assert');
 const fs = require('fs');
 const path = require('path');
-const src = path.join(common.fixturesDir, 'a.js');
+const src = fixtures.path('a.js');
 const dest = path.join(common.tmpDir, 'copyfile.out');
 const { COPYFILE_EXCL, UV_FS_COPYFILE_EXCL } = fs.constants;