Only run integration tests on Python changes (#3610)

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# Rationale for this change
I noticed on my AGENTS.md change that it ran the integration tests. We
haven't (yet) reached issues from ASF on runner usage, but this is a
really easy win. Markdown changes shouldn't trigger integration tests.

## Are these changes tested?
Expecting a no-op. 

## Are there any user-facing changes?

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