test: use common/tmpdir in watch-mode ipc test

Using `path.join(os.tmpdir(), 'file')` on a multi-user system can lead
to file collisions where the file already exists but is owned by a
different user and cannot be removed or overwritten. Other tests in
`parallel/test-watch-mode-files_watcher` use `common/tmpdir` instead
so switch to that for consistency.

PR-URL: #45211
Refs: #44366
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>

test/fixtures/watch-mode/ipc.js

@@ -1,9 +1,9 @@
 const path = require('node:path');
 const url = require('node:url');
-const os = require('node:os');
 const fs = require('node:fs');
+const tmpdir = require('../../common/tmpdir');
 
-const tmpfile = path.join(os.tmpdir(), 'file');
+const tmpfile = path.join(tmpdir.path, 'file');
 fs.writeFileSync(tmpfile, '');
 
 process.send({ 'watch:require': path.resolve(__filename) });

test/parallel/test-watch-mode-files_watcher.mjs

@@ -5,7 +5,6 @@ import tmpdir from '../common/tmpdir.js';
 import path from 'node:path';
 import assert from 'node:assert';
 import process from 'node:process';
-import os from 'node:os';
 import { describe, it, beforeEach, afterEach } from 'node:test';
 import { writeFileSync, mkdirSync } from 'node:fs';
 import { setTimeout } from 'node:timers/promises';
@@ -153,7 +152,7 @@ describe('watch mode file watcher', () => {
     const child = spawn(process.execPath, [file], { stdio: ['pipe', 'pipe', 'pipe', 'ipc'], encoding: 'utf8' });
     watcher.watchChildProcessModules(child);
     await once(child, 'exit');
-    let expected = [file, path.join(os.tmpdir(), 'file')];
+    let expected = [file, path.join(tmpdir.path, 'file')];
     if (supportsRecursiveWatching) {
       expected = expected.map((file) => path.dirname(file));
     }