minor(fix): correct to_date results for formatted pre-epoch datetimes

[buraksenn]

Which issue does this PR close?

• Closes N\A but I can open an issue

Rationale for this change

Formatted to_date inputs are parsed as milliseconds since the Unix epoch and then converted to Date32 days. Integer division truncates toward zero, so negative sub-day timestamps are incorrectly mapped to day 0 instead of day -1.

-- DataFusion before this change
SELECT to_date('1969-12-31 12:00:00', '%Y-%m-%d %H:%M:%S');
-- 1970-01-01

-- PostgreSQL
SELECT to_date('1969-12-31 12:00:00', 'YYYY-MM-DD HH24:MI:SS');
-- 1969-12-31

-- DuckDB
SELECT CAST(strptime('1969-12-31 12:00:00', '%Y-%m-%d %H:%M:%S') AS DATE);
-- 1969-12-31

What changes are included in this PR?

Use Euclidean division when converting formatted timestamp milliseconds to days, preserving the correct date for timestamps before the Unix epoch.

Are these changes tested?

Yes new slt test for this case.

Are there any user-facing changes?

No API changes. Formatted pre-epoch datetimes now return the correct date.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.86%. Comparing base (455a3ad) to head (6d54bdf).
⚠️ Report is 26 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #24049      +/-   ##
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+ Coverage   80.84%   80.86%   +0.01%     
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  Files        1096     1101       +5     
  Lines      373832   375446    +1614     
  Branches   373832   375446    +1614     
==========================================
+ Hits       302240   303587    +1347     
- Misses      53563    53767     +204     
- Partials    18029    18092      +63     

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[kumarUjjawal]

Looks good!

[kumarUjjawal]

Thank you @buraksenn