Avoid accidental on-device array creation in _reduction_init_val.
Avoid accidental on-device array creation in _reduction_init_val.

Revert changes to _reduction_init_val, which is carefully crafted to use classic NumPy functions so lax can pattern match on the reducer monoid.

Instead, don't call _reduction_init_val on the initial argument from NumPy, which might well be a traced value.

PiperOrigin-RevId: 395947318

google/jax,google/jax,google/jax,google/jax