Fix CODEOWNERS

[sebawo]

---

Below is a summarization created by an LLM (gpt-4-0125-preview). Be mindful of hallucinations and verify accuracy.

## Why
The removal of the `@smartcontractkit/test-tooling-team` from the CODEOWNERS file streamlines the review process by directing all future code reviews to the appropriate and updated GitHub team, `@smartcontractkit/devex-tooling`. This change simplifies the management of code ownership.

## What
- **CODEOWNERS**
  - Removed `@smartcontractkit/test-tooling-team` from code owners.
  - Retained `@smartcontractkit/devex-tooling` as the sole code owner. This change ensures that all code reviews are directed to the currently active and relevant team.

[github-actions]

👋 sebawo, thanks for creating this pull request!

To help reviewers, please consider creating future PRs as drafts first. This allows you to self-review and make any final changes before notifying the team.

Once you're ready, you can mark it as "Ready for review" to request feedback. Thanks!