message: ipu_multi_worker_strategy_test: Improve one test
  Summary: Make sure the inputs are different on the different workers.
  Test Plan: Test still passes.
  Reviewers: #tensorflow, #framework_ip_review_-_any_oss_or_third-party_code_use_has_been_approved, davidn
  Maniphest Tasks: T19846
diff: @@ -790,11 +790,12 @@ class IPUMultiWorkerStrategyMultiProcessTest(googletest.TestCase):
  self._run_workers_in_processes(self._test_reduction_in_compiled_cluster,
  cluster_spec)
  - def _test_optimizer_in_compiled_cluster(self, _task_id):
  + def _test_optimizer_in_compiled_cluster(self, task_id):
  strategy, target, sess_config = self._create_test_objects(
  variables_on_host=False)
  - x = 1.5
  + per_worker_x = [i + 1.0 for i in range(strategy.num_replicas_in_sync)]
  + x = per_worker_x[task_id]
  initial_w = 2.0
  learning_rate = 0.5
  @@ -815,13 +816,12 @@ class IPUMultiWorkerStrategyMultiProcessTest(googletest.TestCase):
  config = ipu_utils.auto_select_ipus(config, num_ipus=1)
  ipu_utils.configure_ipu_system(config)
  - num_workers = strategy.num_replicas_in_sync
  [w] = variables.global_variables()
  with session_lib.Session(target=target, config=sess_config) as sess:
  sess.run(w.initializer)
  sess.run(train_op)
  - expected_w = initial_w - num_workers * learning_rate * x
  + expected_w = initial_w - learning_rate * np.sum(per_worker_x)
  self.assertEqual(expected_w, sess.run(w))
  def test_optimizer_in_compiled_cluster(self):
  