Fix: broken disabled select style in the editor area

[dinhtungdu]

Description

In #30141 we added reset style for select which introduced the multiple arrows background issue for select elements inside the editor. This happens because we didn't "reset" the style correctly for the select:disabled's background. This PR fixes this issue by resetting the select:disabled style following the way it's styled in wp-admin/css/forms.css.

Fixes #35133.

How has this been tested?

1. Add a new page.
2. Insert Archives block.
3. Toggle on Display as dropdown.
4. See the dropdown styled correctly.

Screenshots

Before:

After:

Types of changes

Bug fix

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• I've tested my changes with keyboard and screen readers.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR (please manually search all *.native.js files for terms that need renaming or removal).

[github-actions]

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[Aljullu]

Tested and confirming it fixes the issue. Code changes look good as well. Thanks, @dinhtungdu!

[Mamaduka]

Thanks for working on this fix, @dinhtungdu, and congratulations on your first PR 🎉