chore: consolidate testing for closed tcp connections

[mccutchen]

A small drive-by improvement. Still not 100% sure this is the right way to approach these tests, or if they're even necessary or the right idea. E.g. what about TCP connection reuse (though I'm not sure if that's even allowed)?

[github-actions]

🔥 Run benchmarks comparing e422a04 against main:

gh workflow run bench.yaml -f pr_number=48

Note: this comment will update with each new commit.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.37%. Comparing base (aa7a462) to head (e422a04).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #48   +/-   ##
=======================================
  Coverage   92.37%   92.37%           
=======================================
  Files           2        2           
  Lines         459      459           
=======================================
  Hits          424      424           
  Misses         28       28           
  Partials        7        7           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.