perf: Rechunk before we go into grouped gathers

[ritchie46]

fixes #17562

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.68%. Comparing base (d43df08) to head (63a19f5).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17623      +/-   ##
==========================================
+ Coverage   80.66%   80.68%   +0.02%     
==========================================
  Files        1484     1484              
  Lines      195402   195409       +7     
  Branches     2779     2779              
==========================================
+ Hits       157615   157671      +56     
+ Misses      37277    37228      -49     
  Partials      510      510              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.