GH-51638: [CI][C++][Parquet] Update expected JSON output in parquet-reader-test for simdjson 5.0

[tadeja]

Rationale for this change

See #51638 - fractured_json formatting changes with the new simdjson version 5.0 (whitespace, line breaks, key order in tables),
cause parquet-reader-test to fail on four of its tests TestJSONWithLocalFile.JSONOutput...

What changes are included in this PR?

Check simdjson::SIMDJSON_VERSION_MAJOR, and for >= 5 use the new expected formatting (JSON content hasn't changed).
Keep existing expected output formatting for simdjson 4.x

Are these changes tested?

Yes, CI runs pass.

Are there any user-facing changes?

No, only test changes.

Was AI used for this PR?

PR code and description written by:

• Human
• AI

Reviewed before submission by:

• Human
• AI
• Not reviewed

• GitHub Issue: [CI][C++][Parquet] Failure on parquet-reader-test with simdjson 5.x #51638

[Copilot]

Copilot review overview

🟢 Approval recommended

The version-specific expectations match the generated field order, and relevant C++ CI checks pass.

Review effort: Balanced
Findings: None

What changed in this PR

Updates Parquet reader test expectations for simdjson 5.0 formatting while preserving compatibility with 4.x.

Changes:

• Selects expected JSON formatting by simdjson major version.
• Updates four affected JSON-output tests.

File	Description
cpp/​src/​parquet/​reader_test.cc	Adds simdjson 5.x expected output variants.

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[kou]

I think that we can skip these tests with simdjson < 5 to reduce maintenance costs.
I think that testing only with simdjson > 5.0 is enough.

[pitrou]

Or perhaps we can make those tests whitespace-insensitive?

[Copilot]

Copilot review overview

🟡 Changes recommended

Bundled simdjson 4.6.4 builds now skip four tests instead of retaining their existing expectations.

Review effort: Balanced
Findings: 1

Open (1)

• Do not skip formatting assertions for bundled simdjson 4.x · New

[tadeja]

Alright, I've reworked this to skip four JSONOutput tests when simdjson < 5 per @kou's request as I agree that might make most sense later (but might seem premature now that bundled simdjson is still 4.6.4)

@pitrou as mentioned on the issue, I have a demo by 🤖 on my fork tadeja#2 (that checks only the content... but might be radical :))

[raulcd]

pitrou as mentioned on the issue, I have a demo by 🤖 on my fork tadeja#2 (that checks only the content... but might be radical :))

To be honest the diff on that one is smaller than the one here 🤣

[raulcd]

I am happy with this fix (and improving the validation to skip formatting differences on a different PR) to solve the current failures for the release.

[kou]

+1