fix: stabilize flaky resizable-columns integration test

[amanabiy]

Description

The "should recover column widths when the inner state is reset" test reads column width immediately after clicking #reset-state. React hasn't finished re-rendering at that point, so the test intermittently reads the default width instead of the recovered one.

Fix: replace the immediate read with assertColumnWidth, which polls via waitUntil (1s timeout). Same pattern used by adjacent tests in the file.

Related links, issue #, if available: 8ODfAlKbid05

How has this been tested?

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.43%. Comparing base (00a695f) to head (bc99d2a).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4552   +/-   ##
=======================================
  Coverage   97.43%   97.43%           
=======================================
  Files         941      941           
  Lines       29692    29692           
  Branches    10791    10791           
=======================================
  Hits        28930    28930           
  Misses        715      715           
  Partials       47       47           

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