[3.13] gh-62184: Remove _pyio import of _io.FileIO (gh-134192) (gh-134436)

This was added in the add of `_io`, isn't used since bpo-21859 when a
`_pyio` implementation was added which defines `FileIO` lower down in
the file.
(cherry picked from commit 0a68068bd2a5bff98998067a141b17af5be9b750)

Co-authored-by: Cody Maloney <cmaloney@users.noreply.github.com>