Avoid duplicate CheckOverflow evaluation for decimal division

[peterxcli]

What is the problem the feature request solves?

Decimal Divide is currently serialized with two consecutive, equivalent CheckOverflow expressions.

After #5171:

• DecimalPrecision.promote adds an outer wrapper with datatype = Divide.dataType and failOnError = (Divide.evalMode == ANSI).
• CometDivide.convert adds an inner wrapper with the same datatype and overflow mode.

The resulting shape is:

CheckOverflow(type=T, fail=F)
  CheckOverflow(type=T, fail=F)
    Divide(...)

The native planner only removes a CheckOverflow whose child is a matching WideDecimalBinaryExpr, or fuses one whose child is a decimal Cast; it does not collapse nested CheckOverflow expressions (planner.rs).

On successful array-valued decimal-division batches, both wrappers therefore perform the precision scan in CheckOverflow.evaluate.

Describe the potential solution

Stop DecimalPrecision.promote from wrapping decimal Divide, while retaining the specialized wrapper in CometDivide.convert. That wrapper is required to handle Comet's native decimal-division overflow sentinel correctly.

Acceptance criteria:

• Decimal Divide serializes to exactly one CheckOverflow.
• Its datatype equals Divide.dataType.
• failOnError is true only for ANSI mode.
• LEGACY and TRY overflow behavior remains null-producing.
• ANSI overflow behavior remains error-producing.
• Existing divide-by-zero behavior is unchanged.
• Add a proto-level regression covering LEGACY, TRY, and ANSI modes.

Additional context

Raised in review of #5171, while fixing #5075.

[peterxcli]

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