fix grouped sum index for listview array

[onursatici]

Summary

grouped sum fallback should index the groups correctly when summing

[gatesn]

I think a Mask iterator is far faster than value for every function

[onursatici]

Yea but I don't think we have that now. I can add one though separately

[onursatici]

#8258

[codspeed-hq]

Merging this PR will degrade performance by 23.16%

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

❌ 3 regressed benchmarks
✅ 1504 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	chunked_bool_canonical_into[(1000, 10)]	30.3 µs	45.2 µs	-33.03%
❌	Simulation	chunked_varbinview_canonical_into[(1000, 10)]	160.8 µs	197 µs	-18.38%
❌	Simulation	chunked_varbinview_into_canonical[(1000, 10)]	175.6 µs	211.6 µs	-17.02%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing os/grouped-sum-index (49004bb) with develop (340d7be)}