Button: Remove green background color in button preview

[walbo]

Description

Remove the green background color in the button example. The button will then use the default button color. This will also make the style from the theme match the preview.

Fixes #21954

How has this been tested?

Locally with different bundled themes.

Screenshots

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]

👋 Thanks for your first Pull Request and for helping build the future of Gutenberg and WordPress, @walbo! In case you missed it, we'd love to have you join us in our Slack community, where we hold regularly weekly meetings open to anyone to coordinate with each other.

If you want to learn more about WordPress development in general, check out the Core Handbook full of helpful information.

[skorasaurus]

Thanks for including screenshots and the PR; I didn't realize this would be such an easy fix!

I've tested this on a block-based theme (hansen) and the green color background is removed.

[walbo]

I have also tested it on a couple of custom themes and havn't found any issues with the fix.

[stokesman]

I found no issues testing this on a few custom themes. This seems like the way it ought to be 👍 .

[Mamaduka]

It works as expected. Thanks for the contribution, @walbo.