DM-35248: Bind test socket to localhost and not every host

[timj]

Checklist

• ran Jenkins
• added a release note for user-visible changes to doc/changes

[codecov]

Codecov Report

Merging #702 (97cebaa) into main (33b7160) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #702   +/-   ##
=======================================
  Coverage   84.54%   84.54%           
=======================================
  Files         243      243           
  Lines       31785    31785           
  Branches     5954     5954           
=======================================
  Hits        26874    26874           
  Misses       3740     3740           
  Partials     1171     1171           

Impacted Files	Coverage Δ
tests/test_butler.py	97.58% <100.00%> (ø)

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