Remove GlobalStyleSupportFeatureConfig

[nbradbury]

This PR partially fixes #21412 by removing GlobalStyleSupportFeatureConfig from "Features in development." This debug setting defaulted to true so it wasn't necessary to keep it.

Note: The issue mentions that we should also remove SiteIntentQuestionFeatureConfig, but I decided to do that in a separate PR.

To Test:

• Visit the "Features in development" page of debug settings and verify that GlobalStyleSupportFeatureConfig is no longer there.
• Verify that the editor works as expected for both posts & pages

[dangermattic]

	1 Warning
:warning:	PR is not assigned to a milestone.

Generated by :no_entry_sign: Danger

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr21413-fe1d14a
	Commit	fe1d14af4bf10fffabbc8d12a8eff9c6a4a25dad
	Direct Download	wordpress-prototype-build-pr21413-fe1d14a.apk

Note: Google Login is not supported on these builds.

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr21413-fe1d14a
	Commit	fe1d14af4bf10fffabbc8d12a8eff9c6a4a25dad
	Direct Download	jetpack-prototype-build-pr21413-fe1d14a.apk

Note: Google Login is not supported on these builds.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 39.31%. Comparing base (b9405f4) to head (fe1d14a). Report is 3 commits behind head on trunk.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## trunk #21413 +/- ## ========================================== - Coverage 39.31% 39.31% -0.01% ========================================== Files 2121 2120 -1 Lines 98320 98317 -3 Branches 15231 15231 ========================================== - Hits 38651 38649 -2 + Misses 56230 56229 -1 Partials 3439 3439 ```

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