The test previously created two fs.promises.open calls on the
same file with w+ back-to-back, and one of them could fail
when checking the contents of that file if the other happened
to be opening the file for write. Split them into different
tests (with different tmpdir) to avoid the race.
PR-URL: https://github.com/nodejs/node/pull/44380
Refs: https://github.com/nodejs/reliability/issues/354
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>