docs: use ConfigMap for Cilium job based installation example

[mattwillsher]

Pull Request

What? (description)

Passing the command args to cilium CLI results in an error where the list elements are interpreted as a single argument, producing an error. Attempts to split them out lead to issues parsing the capabilities list.

Using a ConfigMap avoids these issues.

#9034 changes the same example.

Why? (reasoning)

I don't understand why the example in the docs didn't work for me, but this new approach worked both when applied directly and when run via the talos Terraform provider.

Acceptance

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• [ ] you linked an issue (if applicable)
• [ ] you included tests (if applicable)
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• [ ] you generated documentation (make docs)
• [ ] you ran unit-tests (make unit-tests)

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