Add per-aggregate argument evaluation metrics for grouped hash aggregation

[kosiew]

Which issue does this PR close?

• Part of Add aggregate specific metrics #23570

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Rationale for this change

Grouped hash aggregation currently exposes a single aggregate_arguments_time metric for all aggregate argument evaluation. This makes it difficult to determine which aggregate expression is responsible for argument evaluation cost when multiple aggregates are present (for example, SUM(a) versus SUM(b)).

This change adds per-aggregate argument evaluation metrics while preserving the existing operator-level metric for compatibility.

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What changes are included in this PR?

• Add an AggregateArgumentMetrics helper that registers one timer per aggregate expression during operator construction.

• Label per-aggregate metrics using the aggregate expression display text (or alias), allowing otherwise identical aggregate functions on different inputs (for example, SUM(a) and SUM(b)) to be distinguished.

• Wrap aggregate argument evaluation with the corresponding per-aggregate timer in:

  • grouped hash aggregation stream
  • migrated hash table aggregation paths
  • ordered aggregation table paths

• Introduce OrderedAggregateTableMetrics to carry both group-by and aggregate argument metrics through ordered aggregation replay/spill paths.

• Factor out a reusable aggregate_metric_label helper for consistent metric labels.

• Preserve the existing aggregate_arguments_time metric so whole-phase timing continues to be reported.

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Are these changes tested?

Yes.

This PR adds and updates tests including:

• test_groupby_aggregate_argument_metrics_distinguish_inputs, which verifies that separate metrics are created for SUM(a) and SUM(b) with distinct metric names and aggregate labels.

• Existing group-by metrics tests updated to use shared aggregate construction helpers.

• Grouped hash aggregation stream tests updated to verify both:

  • the existing aggregate_arguments_time metric remains present and non-zero, and
  • the new per-aggregate metric (agg_expr_0_arguments_time) is emitted and records time.

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Are there any user-facing changes?

Yes.

EXPLAIN ANALYZE and execution plan metrics for the covered grouped hash aggregation paths now include per-aggregate argument evaluation timers (for example, agg_expr_0_arguments_time) with aggregate labels identifying the corresponding aggregate expression, while retaining the existing aggregate_arguments_time metric for compatibility.

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LLM-generated code disclosure

This PR includes LLM-generated code and comments. All LLM-generated content has been manually reviewed.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 92.34234% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.86%. Comparing base (f8b9ed8) to head (a43dd63).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...ysical-plan/src/aggregates/group_values/metrics.rs	88.54%	1 Missing and 14 partials ⚠️
...hysical-plan/src/aggregates/grouped_hash_stream.rs	94.73%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##             main   #24024    +/-   ##
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  Coverage   80.86%   80.86%            
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  Files        1099     1099            
  Lines      374720   374904   +184     
  Branches   374720   374904   +184     
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+ Hits       303015   303183   +168     
- Misses      53614    53623     +9     
- Partials    18091    18098     +7     

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