[3.14] gh-133157: remove usage of _Py_NO_SANITIZE_UNDEFINED in Parser/pegen.c (GH-134048) (#135320)

gh-133157: remove usage of `_Py_NO_SANITIZE_UNDEFINED` in `Parser/pegen.c` (GH-134048)
(cherry picked from commit 754e7c9)

Co-authored-by: Bénédikt Tran <[email protected]>

Author: miss-islington