[3.12] gh-96310: Fix a traceback in argparse when all options in a mutually exclusive...

[3.12] gh-96310: Fix a traceback in argparse when all options in a mutually exclusive group are suppressed (GH-96311) (GH-115767)

Reproducer depends on terminal size - the traceback occurs when there's
an option long enough so the usage line doesn't fit the terminal width.
Option order is also important for reproducibility.

Excluding empty groups (with all options suppressed) from inserts
fixes the problem.
(cherry picked from commit 5f7df88821347c5f44fc4e2c691e83a60a6c6cd5)

Co-authored-by: Daniel Mach <daniel.mach@suse.com>