Update random secrets test_utils.py

[BeibinLi]

Avoid the Gid Guardian's complaints.

Why are these changes needed?

Related issue number

Checks

• [ X] I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://microsoft.github.io/autogen/docs/Contribute#documentation to build and test documentation locally.
• [ X] I've added tests (if relevant) corresponding to the changes introduced in this PR.
• [ X] I've made sure all auto checks have passed.

[gitguardian]

⚠️ GitGuardian has uncovered 4 secrets following the scan of your pull request.

Please consider investigating the findings and remediating the incidents. Failure to do so may lead to compromising the associated services or software components.

🔎 Detected hardcoded secrets in your pull request

GitGuardian id	GitGuardian status	Secret	Commit	Filename
10404693	Triggered	Generic High Entropy Secret	caf7f93	test/oai/test_utils.py	View secret
10404694	Triggered	Generic High Entropy Secret	caf7f93	test/oai/test_utils.py	View secret
10404696	Triggered	Generic High Entropy Secret	caf7f93	test/oai/test_utils.py	View secret
10422482	Triggered	Generic High Entropy Secret	caf7f93	test/oai/test_utils.py	View secret

🛠 Guidelines to remediate hardcoded secrets

1. Understand the implications of revoking this secret by investigating where it is used in your code.
2. Replace and store your secrets safely. Learn here the best practices.
3. Revoke and rotate these secrets.
4. If possible, rewrite git history. Rewriting git history is not a trivial act. You might completely break other contributing developers' workflow and you risk accidentally deleting legitimate data.

To avoid such incidents in the future consider

• following these best practices for managing and storing secrets including API keys and other credentials
• install secret detection on pre-commit to catch secret before it leaves your machine and ease remediation.

---

<sup>🦉 GitGuardian detects secrets in your source code to help developers and security teams secure the modern development process. You are seeing this because you or someone else with access to this repository has authorized GitGuardian to scan your pull request.

Our GitHub checks need improvements? Share your feedbacks!</sup>

[ekzhu]

Thank you @BeibinLi for this effort!