fix(remark-stringify): omit trailing breaks that cannot round-trip

[BetterAndBetterII]

Drop trailing break nodes on stringify so they do not round-trip as a literal backslash under CommonMark. Mid-phrasing breaks are unchanged. Fixes #1477

[github-actions]

Hi! It seems you removed the template which we require. Here are our templates (pick the one you want to use and click *raw* to see its source):

• pull-request-template.md

I won’t send you any further notifications about this, but I’ll keep on updating this comment, and hide it when done!

Thanks,
— bb

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (334415d) to head (f3c551a).

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1497   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            6         6           
  Lines          138       173   +35     
=========================================
+ Hits           138       173   +35     

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[ChristianMurphy]

Thanks @BetterAndBetterII!
I'm not sure the solution direction is fully decided yet for this #1477 (comment)
And when it is, if it requires a change, it would go in mdast-util-to-markdown