Temporarily move Duo Code Review feature category to code_suggestions

What does this MR do and why?

Temporarily move Duo Code Review feature category to code_suggestions

This was required to avoid that other teams are pinged for issues related to Duo Code Review while we do not have a proper category for this feature.

Once we have a proper feature category approved, we can use this MR as a reference to what needs to be moved again to that category.

References

See gitlab-com/www-gitlab-com!140847

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