test: fully reset ghttp server

[piksel]

Follow up to #1117, that should prevent the tests from randomly failing in CI.

[codecov]

Codecov Report

Merging #1121 (4dba9bd) into main (1b405d4) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1121   +/-   ##
=======================================
  Coverage   61.96%   61.96%           
=======================================
  Files          22       22           
  Lines        1438     1438           
=======================================
  Hits          891      891           
  Misses        463      463           
  Partials       84       84           

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