Shadow: revert shadow default presets opt-in to opt-out

[madhusudhand]

What?

This change reverts part of changes from #58766 and #59499.
It is to sync changes from WordPress/wordpress-develop#6309 back to Gutenberg.

Why?

Previous fix causing regression as mentioned here

How?

Restores defaultPresets to true and removes it from appearanceTools.

Testing Instructions

Block theme:

1. Activate a block theme
2. try applying shadow to blocks (button, image) from global styles
3. try applying a shadow from block editor settings to a block (button, image)
4. It should work as expected.
5. add a custom shadow with slug same as core preset (ex: deep) and it should not appear in the list of shadows.

Classic themes:

1. Activate a classic theme
2. Shadow tools should not appear in the block settings panel.
3. Label of the panel should be "Border"

Also, test this regression scenario.

Screenshots or screencast

Fixes: #59989

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: madhusudhand <madhudollu@git.wordpress.org>
Co-authored-by: ajlende <ajlende@git.wordpress.org>
Co-authored-by: mikachan <mikachan@git.wordpress.org>
Co-authored-by: t-hamano <wildworks@git.wordpress.org>
Co-authored-by: andrewserong <andrewserong@git.wordpress.org>
Co-authored-by: carolinan <poena@git.wordpress.org>
Co-authored-by: oandregal <oandregal@git.wordpress.org>
Co-authored-by: swissspidy <swissspidy@git.wordpress.org>
Co-authored-by: getdave <get_dave@git.wordpress.org>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[ajlende]

Thanks for getting the backport to GB opened up.

LGTM 👍

[github-actions]

Warning: Type of PR label mismatch

To merge this PR, it requires exactly 1 label indicating the type of PR. Other labels are optional and not being checked here.

• Type-related labels to choose from: [Type] Automated Testing, [Type] Breaking Change, [Type] Bug, [Type] Build Tooling, [Type] Code Quality, [Type] Copy, [Type] Developer Documentation, [Type] Enhancement, [Type] Experimental, [Type] Feature, [Type] New API, [Type] Task, [Type] Technical Prototype, [Type] Performance, [Type] Project Management, [Type] Regression, [Type] Security, [Type] WP Core Ticket, Backport from WordPress Core.
• Labels found: [Type] Regression, Backport from WordPress Core.

Read more about Type labels in Gutenberg. Don't worry if you don't have the required permissions to add labels; the PR reviewer should be able to help with the task.

[ajlende]

This is a backport to Gutenberg for Trac #60815 and the WordPress/wordpress-develop#6309 fix.

[mikachan]

These changes are in line with the changes in WordPress/wordpress-develop#6309, so I think this is good to land.

[ajlende]

@oandregal added some tests to the core changeset. @madhusudhand can you copy those over here as well?

[ajlende]

Thanks for getting the tests copied over!