test_no_dangling_asyncio_tasks is flaky on my local box (not on CI)

[crusaderky]

Ubuntu 20.04 desktop
distributed 2022.03.0

test_scheduler.py::test_no_dangling_asyncio_tasks fails 20~40 times out of 1000, leaking the task

<Task pending name='Task-4838' coro=<TCP.write() running at /home/crusaderky/github/distributed/distributed/comm/tcp.py:264> cb=[IOLoop.add_future..() at /home/crusaderky/miniconda3/envs/distributed39/lib/python3.9/site-packages/tornado/ioloop.py:688]>

I've never observed this on CI, possibly due to the fact that CI is a lot slower CPU-wise.