BUG: `setdiff1d` for jax.jit and dask NaN-shaped arrays

Follow-up to https://github.com/data-apis/array-api-extra/pull/115

- `setdiff1d` fails when executed inside jax.jit. This is because of a call to `xp.unique*` without an explicit size= parameter.
- By reading the code I'm fairly sure that the function fails if x1 and/or x2 have Dask backend and NaN in their shapes. Lacks a unit test.