[2.3] Update CODEOWNERS to remove @tratcher

[Tratcher]

I am no longer a maintainer of this code.

[Copilot]

Pull Request Overview

This PR removes @Tratcher from the CODEOWNERS file as they are no longer a maintainer of the code. The change systematically removes @Tratcher from all code ownership assignments while preserving other maintainers.

• Removes @Tratcher from all directory ownership assignments
• Removes entire ownership lines for directories where @Tratcher was the sole owner
• Maintains existing co-owners for directories that had multiple maintainers

[dotnet-policy-service]

Hi @@Tratcher. If this is not a tell-mode PR, please make sure to follow the instructions laid out in the servicing process document.
Otherwise, please add tell-mode label.