chore: Remove unneeded growable

[ritchie46]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 80.31%. Comparing base (41318c3) to head (54ed8cd).
Report is 46 commits behind head on main.

Files	Patch %	Lines
crates/polars-arrow/src/array/growable/mod.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #18165      +/-   ##
==========================================
- Coverage   80.35%   80.31%   -0.05%     
==========================================
  Files        1496     1498       +2     
  Lines      197825   198629     +804     
  Branches     2822     2822              
==========================================
+ Hits       158966   159528     +562     
- Misses      38337    38579     +242     
  Partials      522      522              

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