Blueprints Gallery Library: Fix warnings while running add-site.test.tsx

[katinthehatsite]

Related issues

Fixes STU-1716

How AI was used in this PR

It was used to fix the test.

Proposed Changes

This PR ensures that when you run the tests in add-site.test.tsx, the warning about the DOM structure is not present. It solves it by adjusting the DOM structure to the correct one.

Testing Instructions

• Pull the changes from this branch
• Run npm test -- apps/studio/src/modules/add-site/tests/add-site.test.tsx -t "Blueprint preferred versions"
• Confirm that you can not see the warning about:

  Warning: validateDOMNesting(...): <button> cannot appear as a descendant of <button>.                   
      at button

• Run the same test on trunk and confirm that the warning is not there

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[wpmobilebot]

📊 Performance Test Results

Comparing 63ebbfd vs trunk

app-size

Metric	trunk	63ebbfd	Diff	Change
App Size (Mac)	1409.40 MB	1409.40 MB	+0.00 MB	⚪ 0.0%

site-editor

Metric	trunk	63ebbfd	Diff	Change
load	1471 ms	1544 ms	+73 ms	🔴 5.0%

site-startup

Metric	trunk	63ebbfd	Diff	Change
siteCreation	8569 ms	8587 ms	+18 ms	⚪ 0.0%
siteStartup	4941 ms	4935 ms	6 ms	⚪ 0.0%

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Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change (<50ms diff)