refactor: replace tspl with node:test t.plan in connect-timeout tests

[mcollina]

Summary

Replace @matteo.collina/tspl with Node.js core t.plan() in test/connect-timeout.js.

Changes

• Removed tspl import and all tspl(...) calls
• describe block: uses Promise.withResolvers() + raw assert.* (since describe has no test context)
• assertConnectTimeout helper: t.plan(3) + t.assert.* instead of tspl(t, {plan:3})
• autoSelectFamily test: t.plan(5) + wrapped in await new Promise(...) to keep the test function alive for async callback assertions

Testing

• npx borp -p "test/connect-timeout.js"
• npx eslint test/connect-timeout.js

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.44%. Comparing base (cb4c2f1) to head (ac5b1c4).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5518      +/-   ##
==========================================
- Coverage   93.44%   93.44%   -0.01%     
==========================================
  Files         110      110              
  Lines       37328    37328              
==========================================
- Hits        34881    34880       -1     
- Misses       2447     2448       +1     

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