fix(nereids): prevent implicit BigInt/LargeInt to Double cast in join…

[leonard9893]

... type coercion

BigInt and LargeInt types have higher precision (19 and 39 digits respectively) than DoubleType (53-bit mantissa, ~15-17 significant digits). When BigInt/LargeInt are used in join conditions with Float/Double types, the implicit cast to DoubleType loses precision, causing duplicate join results for values beyond 2^53.

Fix: use DecimalV3Type instead of DoubleType as the wider type when joining BigInt/LargeInt with Float/Double types. DecimalV3 preserves exact integer representation.

Closes: #62968

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What problem was fixed and how it was fixed

Problem: When joining a BigInt/LargeInt column with a Float/Double column in a query condition, Doris implicitly casts both sides to DoubleType. DoubleType has only 53-bit mantissa (~15-17 significant digits), which cannot accurately represent BigInt values (up to 19 digits) or LargeInt values (up to 39 digits). This causes duplicate join results and incorrect query results for values beyond 2^53.

Reproduction: This issue was reported in #62968. When a BigInt column containing values larger than 2^53 is joined with a Double column via implicit cast to Double, values that differ in the original BigInt column can become indistinguishable after the Double cast, leading to duplicate matches.

How it was fixed: Instead of casting to DoubleType, the join condition now uses DecimalV3(38, 0) as the wider type when joining BigInt/LargeInt with Float/Double types. DecimalV3 preserves exact integer representation without precision loss.

Which behaviors were modified

Previous behavior: Joining BigInt/LargeInt with Float/Double columns would implicitly cast both to DoubleType, losing precision for BigInt values beyond 2^53 and causing duplicate join results.

Current behavior: The join condition casts to DecimalV3(38, 0) instead of DoubleType, preserving exact integer representation and eliminating false duplicate matches.

Impact: This change only affects join conditions involving BigInt/LargeInt with Float/Double types. Performance impact is negligible as DecimalV3 comparison is efficient. Correctness is improved for edge cases with large integer values.

What features were added

No new features were added. This is a bug fix.

Which code was refactored

No code refactoring was involved.

Which functions were optimized

No functions were optimized. The fix changes the type coercion logic in Nereids planner for join condition type resolution, ensuring precision-preserving type promotion for BigInt/LargeInt vs Float/Double joins.

[hello-stephen]

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1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
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3. What features were added. Why was this function added?
4. Which code was refactored and why was this part of the code refactored?
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