[clang] [clang][NFC] Reduce one of JSON dump tests (PR #195026)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman approved this pull request.

If this is dropping test coverage, @mizvekov please identify explicitly which coverage is relevant so that we can re-add it (perhaps in a separate test file if more appropriate). The discussion about testing theory doesn't seem to be converging but also is orthogonal; as a maintainer, I don't think the current test is in a reasonable state and would prefer to make progress on it over debating whether AST dump tests should or should not be exhaustive, scripted, etc. So barring specific issues with dropped coverage, the changes LGTM as-is.

https://github.com/llvm/llvm-project/pull/195026