chore: Remove obsolete paths from CODEOWNERS

[MoritzThomasHuebner]

Summary

Removed paths that no longer exist

• experimental bazel folder
• docker bazel builder

Test Plan

Run unit tests

Additional Information

• This change is backwards-breaking

[github-actions]

Thanks for opening a PR! 💯

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Howto

• Reviews. The "Reviewers" listed for this PR are the Magma maintainers who will shepherd it.
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More info

Please take a moment to read through the Magma project's

• Contributing Conventions for norms around contributed code

If this is your first Magma PR, also consider reading

• Developer Onboarding for onboarding as a new Magma developer
• Development Workflow for guidance on your first pull request
• CI Checks for points of contact for failing or flaky CI checks
• GitHub-to-Slack mappings for Magma maintainers for guidance on how to contact maintainers on Slack

[maxhbr]

LGTM