fix: overlay positioning for v3 submenus (aka non viewport containers)

[LFDanLu]

Closes

✅ 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 v3 Submenu docs and verify that the submenu renders as expected

🧢 Your Project:

[rspbot]

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[snowystinger]

Tested against #7654 and while it doesn't cause flipping, it does stop it from rendering the popover completely out of view, so it's an improvement for that. I tested some other PRs which appear to have been fixed along the way and didn't find a regression with this change.

I tested in various popover stories with different window widths and heights as well as with position relative etc and didn't find any new issues.

[snowystinger]

Other PRs to check against:
#6333

[rspbot]

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[LFDanLu]

@snowystinger I forgot to revert the previous changes where we duplicated the old calculatePosition code which may have influenced the testing results, pushed an update. Additionally, I tested against #6333 but unfortunately still got the same issue, we will have to investigate that separately. I have the test story stashed locally, lemme know if you wanna check it out

[rspbot]

Build successful! 🎉

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

[LFDanLu]

merging for testing, will need to make a call if it is worth the risk over the current approach