test_main_thread_em_asm_pthread is flaky

[juj]

Timing out on multiple runners:

corez.test_main_thread_em_asm_pthread
wasm2js3.test_main_thread_em_asm_pthread
wasm2jsz.test_main_thread_em_asm_pthread
wasm2jsz.test_main_thread_em_asm_pthread
wasm2js2.test_main_thread_em_asm_pthread

all with

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ERROR: test_main_thread_em_asm_pthread (test_core.wasm2jsz.test_main_thread_em_asm_pthread)
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Traceback (most recent call last):
  File "/home/clb/.pyenv/versions/3.13.3/lib/python3.13/unittest/case.py", line 58, in testPartExecutor
    yield
  File "/home/clb/.pyenv/versions/3.13.3/lib/python3.13/unittest/case.py", line 651, in run
    self._callTestMethod(testMethod)
    ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^
  File "/home/clb/.pyenv/versions/3.13.3/lib/python3.13/unittest/case.py", line 606, in _callTestMethod
    if method() is not None:
       ~~~~~~^^
  File "/home/clb/buildbot/h12dsi-linux-mint22/emscripten_linux_x64/build/emscripten/main/test/common.py", line 1013, in resulting_test
    return func(self, *args)
  File "/home/clb/buildbot/h12dsi-linux-mint22/emscripten_linux_x64/build/emscripten/main/test/test_core.py", line 1988, in test_main_thread_em_asm
    self.do_run_in_out_file_test('test.cpp', cflags=args)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/clb/buildbot/h12dsi-linux-mint22/emscripten_linux_x64/build/emscripten/main/test/common.py", line 2091, in do_run_in_out_file_test
    output = self._build_and_run(srcfile, expected, **kwargs)
  File "/home/clb/buildbot/h12dsi-linux-mint22/emscripten_linux_x64/build/emscripten/main/test/common.py", line 2129, in _build_and_run
    js_output = self.run_js(js_file, engine, args,
                            input=input,
                            assert_returncode=assert_returncode,
                            interleaved_output=interleaved_output)
  File "/home/clb/buildbot/h12dsi-linux-mint22/emscripten_linux_x64/build/emscripten/main/test/common.py", line 1702, in run_js
    raise timeout_error
  File "/home/clb/buildbot/h12dsi-linux-mint22/emscripten_linux_x64/build/emscripten/main/test/common.py", line 1674, in run_js
    jsrun.run_js(filename, engine, args,
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^
                 stdout=stdout,
                 ^^^^^^^^^^^^^^
                 stderr=stderr,
                 ^^^^^^^^^^^^^^
                 assert_returncode=assert_returncode,
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                 input=input)
                 ^^^^^^^^^^^^
  File "/home/clb/buildbot/h12dsi-linux-mint22/emscripten_linux_x64/build/emscripten/main/test/jsrun.py", line 101, in run_js
    proc = subprocess.run(
        command,
    ...<5 lines>...
        timeout=timeout,
        text=True)
  File "/home/clb/.pyenv/versions/3.13.3/lib/python3.13/subprocess.py", line 556, in run
    stdout, stderr = process.communicate(input, timeout=timeout)
                     ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/clb/.pyenv/versions/3.13.3/lib/python3.13/subprocess.py", line 1222, in communicate
    stdout, stderr = self._communicate(input, endtime, timeout)
                     ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/clb/.pyenv/versions/3.13.3/lib/python3.13/subprocess.py", line 2151, in _communicate
    self.wait(timeout=self._remaining_time(endtime))
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/clb/.pyenv/versions/3.13.3/lib/python3.13/subprocess.py", line 1277, in wait
    return self._wait(timeout=timeout)
           ~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/home/clb/.pyenv/versions/3.13.3/lib/python3.13/subprocess.py", line 2055, in _wait
    raise TimeoutExpired(self.args, timeout)
subprocess.TimeoutExpired: Command '['/home/clb/buildbot/h12dsi-linux-mint22/emscripten_linux_x64/build/node/22.16.0_64bit/bin/node', '--stack-trace-limit=50', '--trace-uncaught', '/tmp/emtest_m70jufys/emscripten_test_wasm2jsz_pldezat5/test.js']' timed out after 299.99980795395095 seconds

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