Unexpected keyword argument in generated unit tests for streaming methods

[vam-google]

Affected APIs:

//google/cloud/bigquery/storage/v1/storage_py_gapic_test
//google/cloud/bigquery/storage/v1beta2/storage_py_gapic_test
//google/devtools/build/v1/build_py_gapic_test

Error output:

_______________________ test_append_rows_flattened_error _______________________

    def test_append_rows_flattened_error():
        client = BigQueryWriteClient(
            credentials=ga_credentials.AnonymousCredentials(),
        )
    
        # Attempting to call a method with both a request object and flattened
        # fields is an error.
        with pytest.raises(ValueError):
>           client.append_rows(
                storage.AppendRowsRequest(),
                write_stream='write_stream_value',
            )
E           TypeError: BigQueryWriteClient.append_rows() got an unexpected keyword argument 'write_stream'