V2 Theme.json spacingSizes not applied properly

[richtabor]

Description

A follow-up to #61842 is needed to iron out a quirk. It seems if the spacingSizes has a slug that is not the default values, the control does not apply them properly (tested on a V2 theme.json implementation).

Step-by-step reproduction instructions

1. Edit the Twenty Twenty Four theme.json spacingSizes slugs to use small, large, etc. Also change the name value for each to match.
2. Add a new page.
3. Add a spacer block.
4. Open the Inspector.
5. Set the spacer block to use the presets.
6. Drag it to the right.
7. See the spacing sizes applied out of order.
8. See the spacing sizes name not rendering, only the default numbers.

Screenshots, screen recording, code snippet

CleanShot.2024-05-31.at.14.38.15.mp4

Environment info

Trunk

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes

[richtabor]

				{
					"name": "1",
					"size": "1rem",
					"slug": "x-small"
				},
				{
					"name": "2",
					"size": "min(1.5rem, 2vw)",
					"slug": "small"
				},
				{
					"name": "3",
					"size": "min(2.5rem, 3vw)",
					"slug": "medium"
				},
				{
					"name": "4",
					"size": "min(4rem, 5vw)",
					"slug": "large"
				},
				{
					"name": "5",
					"size": "min(6.5rem, 8vw)",
					"slug": "x-large"
				},
				{
					"name": "6",
					"size": "min(10.5rem, 13vw)",
					"slug": "xx-large"
				}

[ajlende]

Duplicate of #62194