fix(TextArea): fix empty S2 TextArea height jumping when overlays are open

[reidbarber]

Previously, when you had an empty S2 TextArea and opened an overlay, the height of the TextArea would jump +4.5px while the overlay was open.

Questions:

• Could this potentially have alignment issues with labelPosition="side"? Chromatic looks good.

✅ 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:

Go to the new story and open the ContextualHelp. Verify that the TextArea's height does not change when the popover is opened.

🧢 Your Project:

[rspbot]

Build successful! 🎉

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

[yihuiliao]

now that we've changed align-items to start, the label and the placeholder are not aligned when labelPosition: side.

on the pr:

main: