refactor: centralize default Parquet writer properties

[ethan-tyler]

follow up from #4326

Default WriterProperties construction was duplicated across write paths and had drifted where optimize set created_by and other paths didn't.

Adds a shared helper for default Parquet writer properties and wires it through write, JSON, record-batch, checkpoint, and optimize paths. Sets created_by = "delta-rs version <version>" consistently. Existing compression defaults preserved (SNAPPY for standard writes/checkpoints, ZSTD(4) for optimize).

One place to maintain defaults and less drift risk.

[codecov]

Codecov Report

❌ Patch coverage is 98.64865% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.62%. Comparing base (df786bf) to head (e1905a0).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/core/src/delta_datafusion/mod.rs	95.34%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4335      +/-   ##
==========================================
+ Coverage   77.52%   77.62%   +0.10%     
==========================================
  Files         169      170       +1     
  Lines       51995    52106     +111     
  Branches    51995    52106     +111     
==========================================
+ Hits        40309    40448     +139     
+ Misses       9560     9527      -33     
- Partials     2126     2131       +5     

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