Checkout Country input is not wysiwyg styling in editor

[haszari]

Describe the bug

The Country input control looks a bit different in the editor.

• Square corners.
• Semi-transparent background.
• Height bug (too short).

Compare with front end:

I'm assuming this is a regression that snuck in.

To reproduce

Steps to reproduce the behavior:

1. Edit a page with checkout block.
2. Scroll down to country input.

Expected behavior

Consistent appearance in editor and front end.

[Aljullu]

• Square corners.
• Height bug (too short).

This seems to happen because editor CSS is leaking into the block. It could be fixed ensuring our CSS is loaded after wp-edit-post-css (see #3219).

• Semi-transparent background.

This seems to be another instance of #2487, so I think it makes sense investigating it in parallel with other inputs/buttons.