test: fix flaky test-fs-promises-file-handle-read

tmpdir.refresh() cannot be called multiple times reliably on Raspberry
Pi in CI because NFS might optimistically report a path as
removed before it actually is. At least, that's what I think is going
on. Anyway, tmpdir.refresh() is generally designed to be called once,
so let's just call it once.

PR-URL: https://github.com/nodejs/node/pull/37371


Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>