disable towncrier wrapping (#10538)

this PR is a follow up to my comment at
https://github.com/certbot/certbot/pull/10495#discussion_r2683527484

i dislike that jsha chose a slightly different column limit than
towncrier which caused it to generate awkwardly short lines in our
changelog. i also dislike contributors having to remember/know about
towncrier's wrapping behavior when writing changelog entries. i'd like
us to find a way to not have to worry about this

i initially looked into trying to set towncrier's line length limit to a
much higher value, but after searching around
https://towncrier.readthedocs.io/en/stable/configuration.html, i don't
think it's configurable

instead, i'm proposing here that we remove the wrapping entirely.
wrapping was added in response to the discussion at
https://github.com/certbot/certbot/pull/10379#discussion_r2243799585.
every markdown viewer i'm aware of automatically nicely handles wrapping
of long lines in markdown. most also automatically merge manually
wrapped lines to wrap based on the user's display/settings. finally,
since the changelog is automatically edited, i think it'll be rare for
certbot devs to have to manually edit the file

because of all this, i think whether the newsfragment was manually
wrapped or not is largely irrelevant, we shouldn't worry about it, and
we should let people wrap or their newsfragments or not as they see fit

i suppose alternatively we could just let towncrier double/awkwardly
wrap entries since i'm making the case that the wrapping doesn't matter,
but i personally have a slight preference for this approach. let me know
what y'all think

towncrier.toml

@@ -5,7 +5,6 @@ filename = "certbot/CHANGELOG.md"
 title_format = "## {version} - {project_date}"
 issue_format = "[#{issue}](https://github.com/certbot/certbot/issues/{issue})"
 issue_pattern = "\\d+"
-wrap = true
 ignore = []
 
 # Our three custom news fragment types, declared in order of how we'd like them