docs(config): Update wrapped_json.yaml example

[jszwedko]

Summary

Fix the wrapped json example to work with the latest Vector version (v0.42.0). I was going to add tests here, but vector validate --no-environment doesn't execute VRL and so wouldn't have failed. See #15037

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

How did you test this PR?

Ran vector validate locally.

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the "no-changelog" label to this PR.

Checklist

• Please read our Vector contributor resources.
• If this PR introduces changes Vector dependencies (modifies Cargo.lock), please
  run dd-rust-license-tool write to regenerate the license inventory and commit the changes (if any). More details here.

References

• Closes Problem with example "examples/wrapped_json.yaml" #21741

[datadog-vectordotdev]

Datadog Report

Branch report: jszwedko/fix-wrapped_json-example
Commit report: 3b43412
Test service: vector

✅ 0 Failed, 7 Passed, 0 Skipped, 25.47s Total Time