[3.11] gh-90300: Fix undocumented envvars in the Python CLI help (GH-116765) (GH-116797) (GH-116803)

(cherry picked from commit fc4d5fdffe3d9829b118232f35ccee61a27392ee)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
(cherry picked from commit 19ac28bd08fdb16795e6f82ea7bfac73e8f3791b)