[doc] configparser: avoid inline comments. (GH-31247)

People are testing those blocs with the default
inline_comment_prefixes of None, leading to a:

configparser.InterpolationSyntaxError: '$' must be followed by '$' or '{', found: '$ sign ($ is the only character that needs to be escaped)'
(cherry picked from commit 3ac4e783e077ffd7b51c6acc1591002974644051)

Co-authored-by: Julien Palard <julien@palard.fr>