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]

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[ajlende]

Thanks for getting the backport to GB opened up.

LGTM 👍

[github-actions]

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[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!