refactor(rust): Use row encoding in asof join

[orlp]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 3 lines in your changes missing coverage. Please review.

Project coverage is 79.78%. Comparing base (018dfd1) to head (359fc11).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/polars-ops/src/frame/join/asof/groups.rs	85.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #19125      +/-   ##
==========================================
- Coverage   79.81%   79.78%   -0.04%     
==========================================
  Files        1531     1531              
  Lines      208576   208383     -193     
  Branches     2913     2913              
==========================================
- Hits       166466   166249     -217     
- Misses      41559    41583      +24     
  Partials      551      551              

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