chore: cleanup old codeowners (#679)

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### What does this PR do?

Removes the top level codeowners file which is old and has the parent serverless team. Given github prioritizes the .github/ codeowners it wasnt doing anything anyways

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### Motivation

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### Testing Guidelines

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### Additional Notes

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### Types of changes

- [ ] Bug fix
- [ ] New feature
- [ ] Breaking change
- [ ] Misc (docs, refactoring, dependency upgrade, etc.)

### Check all that apply

- [ ] This PR's description is comprehensive
- [ ] This PR contains breaking changes that are documented in the description
- [ ] This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
- [ ] This PR impacts documentation, and it has been updated (or a ticket has been logged)
- [ ] This PR's changes are covered by the automated tests
- [ ] This PR collects user input/sensitive content into Datadog

Author: ava-silver