fix(combobox): remove keydown tab selecting item

[42tte]

Closes #8744

✅ 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:

Old behaviour

1. enter Favorite Animal input
2. press ArrowDown
3. press Tab
4. Aardvark is now selected

---

yarn start:docs
New behaviour

1. enter Favorite Animal input
2. press ArrowDown
3. press Tab
4. no animal is selected

🧢 Your Project: