e2e: fix ConnectionLimit test

[zirain]

fixes: #8456

Don't use t.Errorf which will mark the test as failed.

[netlify]

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Name	Link
🔨 Latest commit	f85d709
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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.11%. Comparing base (a470576) to head (f85d709).
⚠️ Report is 27 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8473      +/-   ##
==========================================
- Coverage   74.13%   74.11%   -0.02%     
==========================================
  Files         242      242              
  Lines       37579    37579              
==========================================
- Hits        27859    27853       -6     
- Misses       7778     7783       +5     
- Partials     1942     1943       +1     

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