Remove padding support from Post Featured Image

[shimotmk]

Fixes: #52349

What?

This PR reverts padding support for Post Featured Image blocks added by #35775.

Why?

If you set padding like this issue, the border will be double marked up.
#52349

Post Featured Image doesn't have content like Cover block, so I don't think it's necessary to set padding.

How?

Testing Instructions

In the trunk branch

1. Open a Post or Page.
2. Place a Post Featured Image block. If you haven't set an eye catch, set it.
3. Set the border.
4. Set overlay
5. Set Padding
6. You can see the overlayed border and two outer borders
7. Switch to this branch to see the padding control disappear.
8. Previously set spacing attributes are removed by the deprecated process.
   For example, the padding is removed when pasting the following HTML.

<!-- wp:post-featured-image {"overlayColor":"black","dimRatio":50,"style":{"spacing":{"padding":{"top":"clamp(1.875rem, 1.303rem + 1.83vw, 2.813rem)","bottom":"clamp(1.875rem, 1.303rem + 1.83vw, 2.813rem)","left":"var:preset|spacing|50","right":"var:preset|spacing|50"}},"border":{"width":"20px"}},"borderColor":"vivid-cyan-blue"} /-->

Testing Instructions for Keyboard

Screenshots or screencast

[jameskoster]

I don't think we should remove the padding control on featured images, it limits design expression unnecessarily.

[jasmussen]

I'd agree, the padding is valuable to have. Can we do something like this instead?

[shimotmk]

Since the specifications are not fixed, I will close it once.