The /parallel/ tests directory is pretty huge, with 1010 tests at the time of writing.
So large, that GitHub has begun truncating it. And, it is pretty hard to scroll though to find something (depending on your editor of choice).

Perhaps we should split it into actual subsystem folders? Does the test runner allow for that?
It would be a bit of a headache again though, like when we moved /simple/ to /parallel/..
cc @nodejs/testing & @nodejs/ctc