Fix incorrect padding on the ThemeUpgradeModal

[okmttdhr]

Related to #85013

Proposed Changes

This PR addresses a regression in the ThemeUpgradeModal, which was introduced in #85013. It fixes padding on the close icon by resetting the style from components.

before	after

Testing Instructions

• Prepare a Free site
• Go to /setup/site-setup/designSetup?siteSlug=<your-site>
• Pick a Premium theme
• Click Unlock theme
• Verify padding is correct

I also confirmed there is no regression on the Live Preview Upgrade modal.

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• https://wpcalypso.wordpress.com/devdocs/docs/testing/index.md for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
• For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-ajp-p2)?

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-91356

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-91356&env=jetpack

[matticbot]

This PR does not affect the size of JS and CSS bundles shipped to the user's browser.

Generated by performance advisor bot at iscalypsofastyet.com.

[matticbot]

This PR modifies the release build for the following Calypso Apps:

For info about this notification, see here: PCYsg-OT6-p2

• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug fix/theme-upgrade-modal-close-icon on your sandbox.

[taipeicoder]

👍