Removes dependency on internal libraries (metric_writer, metrics, experts_utils, config_flags), and replaces the `host_id` and `host_count` functions as recommended by jax 0.2.13.
Removes dependency on internal libraries (metric_writer, metrics, experts_utils, config_flags), and replaces the `host_id` and `host_count` functions as recommended by jax 0.2.13.

PiperOrigin-RevId: 405709430

google/uncertainty-baselines