refactor: Preserve scalar in more places

[coastalwhite]

No description provided.

[ritchie46]

I will wait until after the patch. ^^

[ritchie46]

Alright, let's continue with this one. Can you rebase?

[codecov]

Codecov Report

Attention: Patch coverage is 61.33333% with 29 lines in your changes missing coverage. Please review.

Project coverage is 79.86%. Comparing base (3904774) to head (395fdb0).
Report is 14 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/polars-core/src/frame/column/compare.rs	27.02%	27 Missing ⚠️
crates/polars-python/src/dataframe/general.rs	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #18898      +/-   ##
==========================================
- Coverage   79.86%   79.86%   -0.01%     
==========================================
  Files        1523     1524       +1     
  Lines      207504   207546      +42     
  Branches     2904     2904              
==========================================
+ Hits       165720   165747      +27     
- Misses      41237    41252      +15     
  Partials      547      547              

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