chore: Purge old parquet and scan code

[coastalwhite]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 60.00000% with 6 lines in your changes missing coverage. Please review.

Project coverage is 81.07%. Comparing base (c434669) to head (ba83deb).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/polars-python/src/dataframe/io.rs	0.00%	2 Missing ⚠️
crates/polars-io/src/parquet/read/async_impl.rs	88.88%	1 Missing ⚠️
crates/polars-io/src/parquet/read/read_impl.rs	0.00%	1 Missing ⚠️
crates/polars-pipe/src/pipeline/convert.rs	0.00%	1 Missing ⚠️
crates/polars-plan/src/plans/functions/count.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #22226      +/-   ##
==========================================
+ Coverage   80.74%   81.07%   +0.32%     
==========================================
  Files        1640     1635       -5     
  Lines      235905   233342    -2563     
  Branches     2719     2719              
==========================================
- Hits       190491   189174    -1317     
+ Misses      44771    43525    -1246     
  Partials      643      643              

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