**What happened**:

With the new Backport providers, when calling `DataflowCreatePythonJobOperator` with an empty `py_rerquirments` Dataflow commands always launch inside a virtualenv.

**What you expected to happen**:

The Dataflow command should run locally.


tests/providers/google/cloud/hooks/test_dataflow.py
'parameters': PARAMETERS,
                'environment': {}
            },
            gcsPath='gs://dataflow-templates/wordcount/template_file',
            projectId=TEST_PROJECT,
            location=TEST_LOCATION,
        )
        mock_controller.assert_called_once_with(
            dataflow=mock_conn.return_value,
            job_id=TEST_JOB_ID,
            name=UNIQUE_JOB_NAME,
            num_retries=5,
            poll_sleep=10,
            project_number=TEST_PROJECT,
            location=TEST_LOCATION,
        )
        mock_controller.return_value.wait_for_done.assert_called_once()
    @mock.patch(DATAFLOW_STRING.format('uuid.uuid4'), return_value=MOCK_UUID)
    @mock.patch(DATAFLOW_STRING.format('_DataflowJobsController'))
    @mock.patch(DATAFLOW_STRING.format('DataflowHook.get_conn'))
    def test_start_template_dataflow_with_runtime_env(self, mock_conn, mock_dataflowjob, mock_uuid):
        options_with_runtime_env = copy.deepcopy(RUNTIME_ENV)
        dataflowjob_instance = mock_dataflowjob.return_value
        dataflowjob_instance.wait_for_done.return_value = None
        method = (mock_conn.return_value
                  .projects.return_value
                  .locations.return_value
                  .templates.return_value
                  .launch)
        method.return_value.execute.return_value = {'job': {'id': TEST_JOB_ID}}