Remove synth fix for replacing iam_policy_pb2_grpc (#5755)
Remove synth fix for replacing iam_policy_pb2_grpc (#5755)


dhermes/gcloud-python,tswast/google-cloud-python,dhermes/google-cloud-python,tseaver/google-cloud-python,googleapis/google-cloud-python,jonparrott/google-cloud-python,tseaver/google-cloud-python,tseaver/google-cloud-python,tseaver/gcloud-python,jonparrott/google-cloud-python,dhermes/google-cloud-python,GoogleCloudPlatform/gcloud-python,GoogleCloudPlatform/gcloud-python,googleapis/google-cloud-python,dhermes/google-cloud-python,tseaver/gcloud-python,tswast/google-cloud-python,dhermes/gcloud-python,tswast/google-cloud-python,jonparrott/gcloud-python,jonparrott/gcloud-python