fix(ListBox): prevent closing Combobox when a section header is clicked

[reidbarber]

Fixes #9215

Same as we already do in useSelectableItem:

react-spectrum/packages/@react-aria/selection/src/useSelectableItem.ts

Lines 398 to 399 in 5d472d4

	// Prevent DOM focus from moving on mouse down when using virtual focus
	shouldUseVirtualFocus ? {onMouseDown: e => e.preventDefault()} : undefined

✅ Pull Request Checklist:

• Included link to corresponding React Spectrum GitHub Issue.
• Added/updated unit tests and storybook for this change (for new code or code which already has tests).
• Filled out test instructions.
• Updated documentation (if it already exists for this component).
• Looked at the Accessibility Practices for this feature - Aria Practices

📝 Test Instructions:

🧢 Your Project:

[rspbot]

Build successful! 🎉

• View the storybook
• View the S2 storybook
• View the documentation
• View the S2 docs

[rspbot]

Build successful! 🎉

• View the storybook
• View the S2 storybook
• View the S2 docs
• View the React Aria docs