Remove border CSS from button block

[jffng]

Changes proposed in this Pull Request:

👋 👋

#19595 ensures that the CSS for the core button block is enqueued when a button is rendered on the server. That way, the Jetpack button uses core's button styles.

However there is still some "default" button CSS that overrides the core + theme styles:

This PR removes that CSS, allowing themes to provide a default value for button borders, fonts, and padding via theme.json that applies to Jetpack buttons.

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

No.

Testing instructions:

• Sandbox remotedemo.wordpress.com
• Vist /about and view the jetpack contact form button
• Verify the core + theme button styles are not being overridden by Jetpack's

[matticbot]

Caution: This PR has changes that must be merged to WordPress.com
Hello jffng! These changes need to be synced to WordPress.com - If you 're an a11n, please commandeer and confirm D77955-code works as expected before merging this PR. Once this PR is merged, please commit the changes to WP.com. Thank you!
This revision will be updated with each commit to this PR

[github-actions]

Thank you for your PR!

When contributing to Jetpack, we have a few suggestions that can help us test and review your patch:

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• ✅ Add a "[Status]" label (In Progress, Needs Team Review, ...).
  
• ✅ Add testing instructions.
  
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• ✅ Add changelog entries to affected projects
  

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Jetpack plugin:

• Next scheduled release: May 3, 2022.
• Scheduled code freeze: April 25, 2022.

[oskosk]

Tests well.

• Please add a changelog file

Use `jetpack changelogger add plugins/jetpack` to add a change file.
Guidelines: https://github.com/Automattic/jetpack/blob/master/docs/writing-a-good-changelog-entry.md

[jffng]

Please add a changelog file

👍

[jffng]

@oskosk thank you for the review, anything else I need to do to bring this PR in?

Looks like there is one failing test that I'm not sure what is about / how to address.

[jeherve]

Looks like there is one failing test that I'm not sure what is about / how to address.

The codecov/project check is not required, so you should be good to go now! I've added both the "Needs Team Review" and the "Needs Review" labels to your PR, so someone from your team can review it as well as someone from Crew. Once it's been approved, you'll be able to merge and commit your changes to WordPress.com as well. 👍

[andrewserong]

Nice work @jffng, apologies for the delayed review — I missed the ping while I was AFK.

This is testing nicely for me, sandboxed via https://remotedemo.wordpress.com/about/ — before this PR, hovering over the "Ask me a question" button results in the border changing size, and after this PR, the hover changes the background color but the position / border remains the same 👍

From looking at the code, this looks like a safe change, too — since the Button styles from Gutenberg are loaded, which already include padding settings, etc, and the Jetpack button block uses the same classes as the core block, it looks like we don't need these rules anymore.

LGTM!

[coder-karen]

LGTM, tests well.

[github-actions]

Great news! One last step: head over to your WordPress.com diff, D77955-code, and deploy it.
Once you've done so, come back to this PR and add a comment with your changeset ID.

Thank you!

[coder-karen]

Hey @jffng! Just wanted to check in about the WordPress.com diff (D77955-code) as I notice it is still open and looks like it needs deploying unless other changes were made elsewhere? The diff itself looks to be a little out of date though now with some failing tests.

[jffng]

Ah sorry I missed this ping @coder-karen — just rebased the branch and waiting for the tests to pass, once they ✅ I will deploy it.