[SB7] Move deprecated argTypes.defaultValue to args (Tooltip & Popover)

[sookmax]

I've noticed SB7 deprecated the use of argTypes.defaultValue, and it encourages users to use args instead.

This PR only contains Popover and Tooltip stories as these were the one contained in #5936.

However, a quick search shows that there are several other stories (dnd.stories.tsx, Button.stories.tsx, etc) also make use of argTypes.defaultValue (just wanted to bring awareness of this).

Related Storybook resources on this matter

• [Bug]: Default values on select controls aren't keep as defined storybookjs/storybook#26076 (comment)
• https://storybook.js.org/docs/faq#why-are-my-args-no-longer-displaying-the-default-values (hashtag seems broken unfortunately)

✅ 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:

[yihuiliao]

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