test_pthread_nested_work_queue is flaky

```
======================================================================
ERROR: test_pthread_nested_work_queue (test_core.cores)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/home/chrome-bot/.cache/.vpython-root/store/cpython+tkj8tpr2n0oj8m0t270p0m71s0/contents/lib/python3.8/unittest/case.py", line 60, in testPartExecutor
yield
File "/home/chrome-bot/.cache/.vpython-root/store/cpython+tkj8tpr2n0oj8m0t270p0m71s0/contents/lib/python3.8/unittest/case.py", line 676, in run
self._callTestMethod(testMethod)
File "/home/chrome-bot/.cache/.vpython-root/store/cpython+tkj8tpr2n0oj8m0t270p0m71s0/contents/lib/python3.8/unittest/case.py", line 633, in _callTestMethod
method()
File "/b/s/w/ir/x/w/install/emscripten/test/common.py", line 330, in decorated
f(self, *args, **kwargs)
File "/b/s/w/ir/x/w/install/emscripten/test/test_core.py", line 2522, in test_pthread_nested_work_queue
self.do_run_in_out_file_test('pthread/test_pthread_nested_work_queue.c')
File "/b/s/w/ir/x/w/install/emscripten/test/common.py", line 1777, in do_run_in_out_file_test
output = self._build_and_run(srcfile, expected, **kwargs)
File "/b/s/w/ir/x/w/install/emscripten/test/common.py", line 1815, in _build_and_run
js_output = self.run_js(js_file, engine, args,
File "/b/s/w/ir/x/w/install/emscripten/test/common.py", line 1404, in run_js
raise timeout_error
File "/b/s/w/ir/x/w/install/emscripten/test/common.py", line 1373, in run_js
jsrun.run_js(filename, engine, args,
File "/b/s/w/ir/x/w/install/emscripten/test/jsrun.py", line 102, in run_js
proc = subprocess.run(
File "/home/chrome-bot/.cache/.vpython-root/store/cpython+tkj8tpr2n0oj8m0t270p0m71s0/contents/lib/python3.8/subprocess.py", line 495, in run
stdout, stderr = process.communicate(input, timeout=timeout)
File "/home/chrome-bot/.cache/.vpython-root/store/cpython+tkj8tpr2n0oj8m0t270p0m71s0/contents/lib/python3.8/subprocess.py", line 1028, in communicate
stdout, stderr = self._communicate(input, endtime, timeout)
File "/home/chrome-bot/.cache/.vpython-root/store/cpython+tkj8tpr2n0oj8m0t270p0m71s0/contents/lib/python3.8/subprocess.py", line 1894, in _communicate
self.wait(timeout=self._remaining_time(endtime))
File "/home/chrome-bot/.cache/.vpython-root/store/cpython+tkj8tpr2n0oj8m0t270p0m71s0/contents/lib/python3.8/subprocess.py", line 1083, in wait
return self._wait(timeout=timeout)
File "/home/chrome-bot/.cache/.vpython-root/store/cpython+tkj8tpr2n0oj8m0t270p0m71s0/contents/lib/python3.8/subprocess.py", line 1798, in _wait
raise TimeoutExpired(self.args, timeout)
subprocess.TimeoutExpired: Command '['/b/s/w/ir/cache/builder/emscripten-releases/node-v20.14.0-linux-x64/bin/node', '--stack-trace-limit=50', '--trace-uncaught', '/b/s/w/ir/x/t/emtest_8v4uhk1t/emscripten_test_cores_czw2q07g/test_pthread_nested_work_queue.js']' timed out after 299.9998672489992 seconds

```