gh-134954: Hard-cap max file descriptors in subprocess test fd_status (#134955)

* Hard-cap max file descriptors in subprocess test fd_status

On some systems, `SC_OPEN_MAX` may return a very large value (i.e. 10**30), leading to the subprocess test timing out (or run forever).
Prevent this situation by applying a hard cap on how many file descriptors are checked.

* Fix typo in usage docstring

s/fd_stats/fd_status/