Remove legacy CPU custom calls.
JAX v0.4.38 (released Dec 17, 2024) no longer lowered to any legacy CPU custom calls. Following our export compatibility guide (https://docs.jax.dev/en/latest/export/export.html#ensuring-forward-and-backward-compatibility), the remaining legacy custom calls can be removed on June 15, 2025, 180 days after the 0.4.38 release.
PiperOrigin-RevId: 772126428
