[SPARK-57659][CORE] Fix ArrayWrappers int[]/long[] comparator overflow for opposite-sign values

[aviyehuda]

What changes were proposed in this pull request?

ComparableIntArray and ComparableLongArray in ArrayWrappers now compare elements with Integer.compare and Long.compare instead of subtraction.

A unit test (testOppositeSignArrayKeyComparison) was added to cover MIN_VALUE vs MAX_VALUE for both int[] and long[].

Why are the changes needed?

ArrayWrappers is used as a key comparator in InMemoryStore for array-typed indices. The previous implementation compared elements via subtraction:

int diff = array[i] - other.array[i];   // int[]
long diff = array[i] - other.array[i];  // long[]

For large opposite-sign values (e.g. Integer.MIN_VALUE vs Integer.MAX_VALUE), subtraction overflows and can return the wrong sign, breaking sort order and map lookups. The long[] path tried to mitigate this with diff > 0 ? 1 : -1, but overflow can still flip the sign of diff, so the result is still wrong.

Does this PR introduce any user-facing change?

No.

How was this patch tested?

Added testOppositeSignArrayKeyComparison in ArrayWrappersSuite.

build/sbt 'kvstore/testOnly *ArrayWrappersSuite'
Both tests in the suite passed.

Was this patch authored or co-authored using generative AI tooling?

No.

[uros-b]

@aviyehuda Please note that @LuciferYang was already working on this: #56731.

[uros-b]

@aviyehuda Please note that @LuciferYang was already working on this: #56731.

I recommend closing the current PR as a duplicate of existing work.

[uros-b]

Closing as duplicate of #56731.
Thank you @aviyehuda and @LuciferYang!