Fix [BS-3418](https://linear.app/affine-design/issue/BS-3418/折叠的embed-doc调整宽度时，会出现一个最小高度，不需要这个)
This PR keeps the content of embed-synced-doc rendered (but clipped) when it is collapsed, to ensure accuracy in height calculation of content.
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## Summary by CodeRabbit
- **Bug Fixes**
- Improved the display logic for embedded synced document editors, ensuring the editor and overlay are always rendered regardless of the folded state.
- **Tests**
- Updated test assertions to more accurately check whether embedded editor content is within the viewport, enhancing reliability of visibility checks.
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