fix: mutiny-test-utils not test-scoped in some cases

[Felk]

This caused some test dependencies to unnecessarily ship into production code, which e.g. trips CVE scanners to flag assertj's CVE-2026-24400.

I didn't find any hints in the commit history indicating that this was on purpose.

Tests passed locally, except AssertSubscriberTest which tripped over LF vs CRLF since I ran them on Windows

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.10%. Comparing base (14e915d) to head (177be95).
⚠️ Report is 23 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2062      +/-   ##
============================================
+ Coverage     89.00%   89.10%   +0.09%     
- Complexity     3115     3117       +2     
============================================
  Files           412      412              
  Lines         13296    13296              
  Branches       1687     1687              
============================================
+ Hits          11834    11847      +13     
+ Misses          822      820       -2     
+ Partials        640      629      -11     

see 12 files with indirect coverage changes

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[jponge]

Good catch @Felk 👏

Thanks for the contribution!