Intermittent iOS buildbot failure in test_sock_client_racing

Bug report

Bug description:

This is failing on about 10% of attempts. Usually it passes on a rerun:

• https://buildbot.python.org/#/builders/1380/builds/6364
• https://buildbot.python.org/#/builders/1380/builds/6374

But sometimes it fails on the rerun:

• https://buildbot.python.org/#/builders/1380/builds/6331
• https://buildbot.python.org/#/builders/1380/builds/6403

 ERROR: test_sock_client_racing (test.test_asyncio.test_sock_lowlevel.KqueueEventLoopTests.test_sock_client_racing)
 ----------------------------------------------------------------------
 Traceback (most recent call last):
   File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/3DAA3568-C09B-454E-9E2B-4749EEB89567/iOSTestbed.app/python/lib/python3.15/test/test_asyncio/test_sock_lowlevel.py", line 273, in test_sock_client_racing
     self.loop.run_until_complete(asyncio.wait_for(
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
         self._basetest_sock_send_racing(listener, sock), 10))
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/3DAA3568-C09B-454E-9E2B-4749EEB89567/iOSTestbed.app/python/lib/python3.15/asyncio/base_events.py", line 724, in run_until_complete
     return future.result()
            ~~~~~~~~~~~~~^^
   File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/3DAA3568-C09B-454E-9E2B-4749EEB89567/iOSTestbed.app/python/lib/python3.15/asyncio/tasks.py", line 488, in wait_for
     return await fut
            ^^^^^^^^^
   File "/Users/buildbot/Library/Developer/CoreSimulator/Devices/4F9AFDE7-A49A-46AD-B161-FCA22E48EA55/data/Containers/Bundle/Application/3DAA3568-C09B-454E-9E2B-4749EEB89567/iOSTestbed.app/python/lib/python3.15/test/test_asyncio/test_sock_lowlevel.py", line 196, in _basetest_sock_send_racing
     sock.send(b' ' * size)
     ~~~~~~~~~^^^^^^^^^^^^^
 ConnectionResetError: [Errno 54] Connection reset by peer

@freakboy3742: FYI

CPython versions tested on:

CPython main branch

Operating systems tested on:

Other

从 test/test_asyncio/test_sock_lowlevel.py 开始，重点查看 KqueueEventLoopTests.test_sock_client_racing 和 _basetest_sock_send_racing，然后比较关联的 iOS buildbot 失败记录和重新运行结果。完成的标准是：该测试在 iOS buildbot 上不再间歇性失败，同时仍能检测到真实的 socket 错误。