Invalid inter-file ordering in eq_properties()

[alamb]

Describe the bug

• Posthumously filing to track fix: validate inter-file ordering in eq_properties() #20329

TLDR: just because the files themselves are sorted doesn't mean the partition streams are sorted.

• eq_properties() in FileScanConfig blindly trusted output_ordering (set from Parquet sorting_columns metadata) without verifying that files within a group are in the correct inter-file order
• EnforceSorting then removed SortExec based on this unvalidated ordering, producing wrong results when filesystem order didn't match data order

To Reproduce

No response

Expected behavior

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Additional context

No response

[alamb]

Fixed by #20329