[3.11] gh-90300: Document equivalent -X options for envvars in the Python CLI help (GH-116756) (GH-116786) (GH-116796)

(cherry picked from commit 991710af022f27db862ff1399178bcc76b062669)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
(cherry picked from commit 8c6db45ce34df7081d7497e638daf3e130303295)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>