Apply review feedback: rename confirmButtonRef and add Storybook args support

[Copilot]

Addresses review feedback from PR #7510 to improve the SettingMaxHeight story implementation for better clarity and e2e/VRT test compatibility.

Changelog

Changed

• Renamed confirmButtonRef to closeButtonRef in SettingMaxHeight story to accurately reflect the element it references
• Updated SettingMaxHeight story to accept Storybook Args parameter, enabling e2e/VRT tests to control overlay state via args: {open: true}
• Updated render condition to isOpen || open to support both internal state and Storybook args
• Updated useFocusTrap disabled condition to !isOpen && !open to match render logic

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why

Testing & Reviewing

Story now follows the same pattern as DialogOverlay and DropdownOverlay for args handling. Verify the story renders correctly in Storybook with args: {open: true}.

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github (Learn more about how to run integration tests)

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[github-actions]

👋 Hi, this pull request contains changes to the source code that github/github-ui depends on. If you are GitHub staff, test these changes with github/github-ui using the integration workflow. Or, apply the integration-tests: skipped manually label to skip these checks.

[github-actions]

👋 Hi, this pull request contains changes to the source code that github/github-ui depends on. If you are GitHub staff, test these changes with github/github-ui using the integration workflow. Or, apply the integration-tests: skipped manually label to skip these checks.