Issue title: Twenty Twenty-One: No global style option on Atomic Sites
 Issue body: ## Summary

Twenty Twenty-One has no option to change Global Styles. If we have changed the custom font while using a different block based theme, and now we want to change the font to the default theme font we need to change the theme, reset the font to default, and change our theme back to Twenty Twenty-One.

UPDATE: This issue is limited to Atomic Sites.

## Steps to replicate

1- Go to any page editor while using Twenty Twenty-One

## Result

Global styles option won't appear. 

## Expected

To see the Global Styles option like any other block based theme. 

![Markup 2021-02-06 at 12 47 38](https://user-images.githubusercontent.com/24919469/107127117-954b3e80-6879-11eb-9ae9-378dced68871.png)


* User report: #3712817-zd


 Comments: 
 Comment 0: This looks like an issue with the Editing Toolkit and corresponding features, not a themes issue, so I've moved it to wp-calypso.
 Comment 1: +1 33429033-hc

Theme: Exford

Global Styles showed up after activating plugin WordPress.com Editing Toolkit.
 Comment 2: Another issue it seems. 

4712079-ZEN

Theme: Twenty Twenty One

User has active Editing Toolkit plugin:

<img width="791" alt="Screenshot 2022-01-23 at 17 17 09" src="https://user-images.githubusercontent.com/71094068/150685437-8ac6e28a-ac7d-4070-a877-e14a8f9d3062.png">

Still no option for Global Styles in the editor. 


 Comment 3: @Sandkorner For your user's case with `twentytwentyone`, this is because the site had the incorrect version symlinked.

The Atomic platform serves two versions of the theme, the upstream version from WordPress.org and a special WPCOM version.

In some cases a WPCOM site might end up with the WPORG version symlinked.

To resolve, we can break the symlink and then install the theme from Calypso -- the proper WPCOM version is installed.

I fixed it for that specific site and discussed with the HE working on the issue at the time @ahmadbaig1 
p1643046046173000-slack-C3GP81E05 

#### Workaround

1. Remove the folder for twentytwentyone to break the symlink.
2. Reinstall twentytwentyone via Calypso, WP-Admin, or `wp theme install twentytwenty.` 

This will get the proper WPCOM-specific version symlinked on your WoA sites.

#### Internal discussion

More on this internally here: p9o2xV-1LC-p2#comment-5395

cc @jeffikus @scruffian it can be a theme issue, I suspect it is in most cases. But, more of a platform symlinking issue. 
 Comment 4: @kriskorn pinging you to see if you get the impression this is a platform level issue which still needs addressing? I'm only seeing one additional report in the past year...
 Comment 5: **Support References**

*This comment is automatically generated. Please do not edit it.*


- [ ] 3712817-zen
- [ ] 3759469-zen
- [ ] 3801920-zen
- [ ] 3802882-zen
- [ ] 4343666-zen
- [ ] 4370483-zen
- [ ] 4712079-zen

 Comment 6: @jordesign I can see that with a properly symlinked Twenty Twenty-One theme, the Global Styles option is there, so it seems the issue might mostly happen only when there is a .org version of the theme active on a site, [as Joshua has described here](https://github.com/Automattic/wp-calypso/issues/59396#issuecomment-1020380212). 

With that said, I think we can go ahead and close this one and help customers out with properly activating a symlinked theme to see Global Styles. 
 Comment 7: Awesome - i'd agree with that too. Thanks for the gut check - consider it closed!
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