gh-88753: Make BooleanOptionalAction's addition of default to help more similar to other actions (#27808)

Help for other actions omit the default value if default is SUPPRESS or
already contains the special format string '%(default)'.  Add those
special cases to BooleanOptionalAction's help formatting too.

Fixes https://bugs.python.org/issue44587 so that default=SUPPRESS is not
emitted.

Fixes https://bugs.python.org/issue38956 as this code will detect
whether '%(default)s' has already been specified in the help string.

Signed-off-by: Micky Yun Chan (michiboo): <chanmickyyun@gmail.com>
Co-authored-by: Micky Yun Chan <michan@redhat.com>