[3.8] gh-95778: Mention sys.set_int_max_str_digits() in error message...

[3.8] gh-95778: Mention sys.set_int_max_str_digits() in error message (GH-96874) (GH-96877) (GH-97835)

[3.9] gh-95778: Mention sys.set_int_max_str_digits() in error message (GH-96874) (GH-96877)

When ValueError is raised if an integer is larger than the limit,
mention sys.set_int_max_str_digits() in the error message.

(cherry picked from commit e841ffc9)

Co-authored-by: Ned Deily <nad@python.org>
(cherry picked from commit 41188134)

Co-authored-by: Victor Stinner <vstinner@python.org>