[Fundamentals] Update Registrar account token support

[CQMHV]

Summary

• Update the Account API token compatibility matrix to mark Registrar as supported.
• Reflect successful verification of Registrar read endpoints, the sandbox registration workflow, and the production registration workflow with an account-owned API token.

Fixes #32939

Documentation checklist

• The change adheres to the documentation style guide.
• An issue has been opened for the out-of-date information that this PR fixes.

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Review

✅ No issues found in commit 7c1543f.

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