perf: only rechunk once per aggregate

[orlp]

Fixes #16457.

[codecov]

Codecov Report

Attention: Patch coverage is 79.66102% with 12 lines in your changes are missing coverage. Please review.

Project coverage is 81.45%. Comparing base (ee25cb7) to head (1810dbc).
Report is 5 commits behind head on main.

Files	Patch %	Lines
...s-core/src/frame/group_by/aggregations/dispatch.rs	79.66%	12 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16469      +/-   ##
==========================================
- Coverage   81.46%   81.45%   -0.02%     
==========================================
  Files        1409     1409              
  Lines      184722   184746      +24     
  Branches     2971     2971              
==========================================
- Hits       150491   150489       -2     
- Misses      33711    33737      +26     
  Partials      520      520              

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