Boost: Ensure LCP Errors are not partially hidden

[LiamSarsfield]

Proposed changes:

• Modifies the CSS to ensure that the FoldingElement component considers the gap between the expandable button, and the error content as actual height.

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
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Jetpack product discussion

Does this pull request change what data or activity we track or use?

Testing instructions:

• Trigger an LCP Optimization Error (See Boost: Surface Error details for LCP Optimization #43647) for instructions.
• Verify that the error messages are fully legible/not partially hidden as per screenshots:

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After

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Code Coverage Summary

This PR did not change code coverage!

That could be good or bad, depending on the situation. Everything covered before, and still is? Great! Nothing was covered before? Not so great. 🤷

Full summary · PHP report · JS report

[dilirity]

Nice! Thanks for fixing this!