datafusion

35b2e359 - fix: `array_distinct` inner nullability causing type mismatch (#18104)

fix: `array_distinct` inner nullability causing type mismatch (#18104) ## Which issue does this PR close? - Closes #17416. ## Rationale for this change `array_distinct`'s inner return type is always `nullable`, however `general_array_distinct` maintain input nullability, causing type mismatch error. I believe the same error happens for `array_union` and `array_intersect` (in `set_ops.rs`). I can include the fix for those in this PR or maybe another separated PR. ## What changes are included in this PR? - Match return type nullability for `array_distinct`. ## Are these changes tested? Yes. I tried to add unit tests checking return types (similar to #15901), but it wasn't clear to me whether the added tests could verify the issue #17416. So I switched to the integration test. - Added test for `List` with inner `nullability = true / false`. - I did not added tests for `LargeList`, I don't think it needed because the code path for the return type is identical to `List`. ## Are there any user-facing changes? I don't think so.