❎ Remove RLOO example test

[qgallouedec]

What does this PR do?

We don't test examples. We only test scripts (trl/scripts).

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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  Pull Request section?
• Was this discussed/approved via a GitHub issue? Please add a link
  to it if that's the case.
• Did you make sure to update the documentation with your changes? Here are the
  documentation guidelines.
• Did you write any new necessary tests?

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Anyone in the community is free to review the PR once the tests have passed. Feel free to tag
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[HuggingFaceDocBuilderDev]

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