fix(testing): record converged gas optimization limit

[RekCuy63]

🗒️ Description

The gas optimization binary search already verifies the converged value with minimum_gas_limit, but the recorded gas_optimization field still used the last loop-local current_gas_limit.

When the final probe is a failing candidate, this stores a value that is one step below the actual minimum gas limit and propagates the wrong optimization result to the JSON output used by follow-up analysis.

This PR records minimum_gas_limit after convergence and adds a regression test to lock in the expected bookkeeping behavior.

🔗 Related Issues or PRs

N/A.

✅ Checklist

• All: Ran fast static checks to avoid unnecessary CI fails, see also Code Standards and Enabling Pre-commit Checks:

  just static

• All: PR title adheres to the repo standard - it will be used as the squash commit message and should start type(scope):.
• All: Considered updating the online docs in the ./docs/ directory.
• All: Set appropriate labels for the changes (only maintainers can apply labels).
• Tests: Ran mkdocs serve locally and verified the auto-generated docs for new tests in the Test Case Reference are correctly formatted.
• Tests: For PRs implementing a missed test case, update the post-mortem document to add an entry the list.
• Ported Tests: All converted JSON/YML tests from ethereum/tests or tests/static have been assigned @ported_from marker.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.25%. Comparing base (47782b3) to head (04b6f79).

Additional details and impacted files

@@               Coverage Diff                @@
##           forks/amsterdam    #2671   +/-   ##
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  Coverage            86.25%   86.25%           
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  Files                  599      599           
  Lines                37032    37032           
  Branches              3795     3795           
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  Hits                 31943    31943           
  Misses                4525     4525           
  Partials               564      564           

Flag	Coverage Δ
unittests	86.25% <ø> (ø)

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