Create New Patterns Page is using post editor when it supposed to be a Site Editor when you create patterns

[Saoming]

Describe the bug
Create New Patterns Page uses a post editor when it is supposed to be a Site Editor when you create patterns.

To Reproduce
Create Patterns from Site Editor as type wp_block

Expected Results

What I am getting right now:

[miksansegundo]

This issue sounds like #554, which was previously fixed by #557

[miksansegundo]

I tested the toggle for "Layout: Inner blocks use content width" in the pattern directory editor, and it seems not to be working because the styles are missing.

I was expecting to find the following styles because they are present in the Site editor, but they are not present in the pattern directory editor:

The only styles that I can find are the following:

@Saoming mentioned to me that those styles were working last month. I'm wondering if this recent commit is somehow related to the issue.

[ryelle]

Closing this in favor of the discussion on #658.