Update path for CODEOWNERS

[RissyRan]

Description

Update the path due to recent restructure.

• Confirmed with Luke src/maxtext/elastic_train.py is expected to remove
• Remove duplicated owners and format clean up

Tests

Manual check

Checklist

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• I have necessary comments in my code, particularly in hard-to-understand areas.
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• I have made or will make corresponding changes to the doc if needed, including adding new documentation pages to the relevant Table of Contents (toctree directive) as explained in our documentation.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[github-actions]

🤖 Hi @RissyRan, I've received your request, and I'm working on it now! You can track my progress in the logs for more details.

[github-actions]

## 📋 Review Summary

This PR successfully updates the paths in the CODEOWNERS file to reflect the recent codebase restructure, moving away from src/MaxText to lowercase src/maxtext. The removal of elastic_train.py paths is also correctly handled.

🔍 General Feedback

• Path Clarity: Several entries targeting directories were updated without trailing slashes. It's best practice in CODEOWNERS to append / to directory paths.
• Root Files: Changing *.md to docs means root-level markdown files (e.g., README.md) are no longer tracked in CODEOWNERS. Consider if this was the intent.
• Cleanup: Some existing duplicate usernames (e.g. @suexu1025) were preserved during the path rename, which have been noted for cleanup.

[bvandermoon]

LGTM, thanks @RissyRan. There is a copybara change that goes along with this as well. I'll send it to in case you haven't seen it already