Previewing a scheme with an unfocused appearance set straight up doesn't work

[zadjii-msft]

Came across this working on ragnarok. Repros on main, and likely back to wherever the pair of "scheme previewing" and "unfocused appearance" exist.

Related to #11067, but... different.

• Use some variety of this profile:

            {
                "background": "#012456",
                "tabColor": "#012456",
                "closeOnExit": "graceful",
                "colorScheme": "Campbell Powershell",
                "unfocusedAppearance": {
                    "colorScheme": "Solarized Light",
                    "opacity": 50,
                    "background": "#222222",
                },
                "font": 
                {
                    "face": "Courier New",
                    "size": 10
                },
                "guid": "{61c54bbd-c2c6-5271-96e7-009a87ff44bf}",
                "name": "PowerShell",
                "opacity": 80,
            },

• Try to select a color scheme with the command palette:

So yea, that's all sorts of weird.

I'm not going to be able to fix that in ragnarok, I just thought we should know.