minor(test): cover partially ordered aggregate spilling

[buraksenn]

Which issue does this PR close?

• Not closes but part of Improve test coverage for spilling (memory-limited) sort/aggregation/sort-merge-join #13431

Rationale for this change

GroupedHashAggregateStream supports spilling for partially sorted group input, but existing aggregate spill tests only cover unordered (GroupOrdering::None) input. The GroupOrdering::Partial + OutOfMemoryMode::Spill path, including spilling sorted intermediate state and merging it back, does not have direct coverage.

What changes are included in this PR?

added test coverage for the case above

Are these changes tested?

test only change and it can be tested via:

cargo test --test sqllogictests -- ordered_aggregate_spill

Are there any user-facing changes?

no test only change

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.70%. Comparing base (994fc81) to head (5f5470e).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #23947   +/-   ##
=======================================
  Coverage   80.69%   80.70%           
=======================================
  Files        1095     1095           
  Lines      372626   372554   -72     
  Branches   372626   372554   -72     
=======================================
- Hits       300700   300658   -42     
+ Misses      53978    53926   -52     
- Partials    17948    17970   +22     

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[2010YOUY01]

LGTM, thank you!

This suggestion is totally optional, it would be great to move it to sqllogictest, due to 1. the test can be stronger as it exercises the behavior end-to-end 2. easier to maintain (I found rust tests regularly need updates during refactors, and they're harder to review)

To do that, sqllogictest provides Rust hooks to setup tables with orders, and we can use explain/explain analyzes to assert if the ordered path is triggered, and if spill happens.