(CAT-2026) Update how pdk test unit --list detects an error

[david22swan]

A recent change has caused the information returned to be in a slightly different format.
Message returned may be different, and include additional details.

Checklist

• 🟢 Spec tests.
• 🟢 Acceptance tests.
• Manually verified.

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.

Project coverage is 88.50%. Comparing base (9041f64) to head (e1c7350).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/pdk/tests/unit.rb	33.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1388      +/-   ##
==========================================
- Coverage   88.52%   88.50%   -0.02%     
==========================================
  Files         127      127              
  Lines        5334     5334              
==========================================
- Hits         4722     4721       -1     
- Misses        612      613       +1     

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[LukasAud]

LGTM