Unfilter RequiresPreviewFeatures attribute

[gewarren]

Contributes to #6861

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label.

[opbld31]

Docs Build status updates of commit 1cdd517:

✅ Validation status: passed

File	Status	Preview URL	Details
xml/_filter.xml	✅Succeeded

For more details, please refer to the build report.

Note: Broken links written as relative paths are included in the above build report. For broken links written as absolute paths or external URLs, see the broken link report.

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