Remove explicit initialize_tpu_system call from model garden.

PiperOrigin-RevId: 290354680

official/utils/misc/tpu_lib.py

@@ -30,5 +30,4 @@ def tpu_initialize(tpu_address):
       tpu=tpu_address)
   if tpu_address not in ('', 'local'):
     tf.config.experimental_connect_to_cluster(cluster_resolver)
-  tf.tpu.experimental.initialize_tpu_system(cluster_resolver)
   return cluster_resolver