Use manual configuration for test_reduction
Use manual configuration for test_reduction

The example relies on a single block being launched, but a forall isn't
guaranteed to generate a configuration with a single block - for
example, on the RTX A6000 it creates the configuration `[2, 768]`.

Explicitly configuring the launch resolves this issue.

cpcloud/numba,numba/numba,cpcloud/numba,numba/numba,cpcloud/numba,numba/numba,numba/numba,cpcloud/numba,numba/numba,cpcloud/numba