fix: Column selection wasn't applied when reading CSV with no rows

[nameexhaustion]

Fixes #16606

[codecov]

Codecov Report

Attention: Patch coverage is 54.54545% with 10 lines in your changes missing coverage. Please review.

Project coverage is 81.44%. Comparing base (ddf8126) to head (d64dde8).
Report is 3 commits behind head on main.

Files	Patch %	Lines
crates/polars-io/src/csv/read/read_impl.rs	54.54%	10 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16739      +/-   ##
==========================================
- Coverage   81.45%   81.44%   -0.02%     
==========================================
  Files        1413     1413              
  Lines      186096   186195      +99     
  Branches     2776     2776              
==========================================
+ Hits       151588   151650      +62     
- Misses      33988    34025      +37     
  Partials      520      520              

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