Disable async dispatch on JAX CPU for a jax_cfd test, i.e., opt out of the change introduced in https://github.com/google/jax/pull/20470, as it is causing some real failures under tsan.

Disable async dispatch on JAX CPU for a jax_cfd test, i.e., opt out of the change introduced in https://github.com/google/jax/pull/20470, as it is causing some real failures under tsan. #906