gh-95778: Mention sys.set_int_max_str_digits() in error message (GH-96874)

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 e841ffc915e82e5ea6e3b473205417d63494808d)

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