chore(config): Fix `InlineSingleUseReferencesVisitor` failing merges

[bruceg]

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Summary

The above visitor is intended to inline schemas in the references section for which there is only a single reference. This visitor is, however, unable to detect some cases where there are in fact multiple references, ending up inlining the schema multiple times. This has led to bloat in generated schemas.

In the core Vector schema, this affects 121 structures, shaving 844 lines off of the generated schema.

I've labelled this as a chore as it doesn't actually make any functional change to the result.

Change Type

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

Is this a breaking change?

• [ ] Yes
• [ ] No

How did you test this PR?

Does this PR include user facing changes?

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

Notes

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References

[datadog-vectordotdev[bot]]

Datadog Report

Branch report: bruceg/fix-inline-single-visitor Commit report: 1c6f57e Test service: vector

:white_check_mark: 0 Failed, 7 Passed, 0 Skipped, 25.26s Total Time

[pront]

There's a failing check: https://github.com/vectordotdev/vector/actions/runs/15645373779/job/44081780346?pr=23207