fix: Skip statistics deserialization for Null columns in Parquet

[0xRozier]

Fixes #26974

Return Ok(None) early for D::Null in deserialize_all, consistent with Dictionary, FixedSizeList, and Struct. This prevents a ShapeError caused by incomplete statistics arrays when predicate pushdown is used on a Null column with a schema override.

No use of AI

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.39%. Comparing base (4cd2447) to head (45b8ab6).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #27021      +/-   ##
==========================================
+ Coverage   80.92%   81.39%   +0.46%     
==========================================
  Files        1809     1809              
  Lines      249500   249497       -3     
  Branches     3140     3140              
==========================================
+ Hits       201919   203078    +1159     
+ Misses      46776    45614    -1162     
  Partials      805      805              

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