**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
mock_jobs_list = (
            self.mock_dataflow.projects.return_value.
            locations.return_value.
            jobs.return_value.
            list
        )
        mock_jobs_list.return_value.execute.return_value = {
            "jobs": []
        }
        (
            self.mock_dataflow.projects.return_value.
            locations.return_value.
            jobs.return_value.
            list_next.return_value
        ) = None
        dataflow_job = _DataflowJobsController(
            dataflow=self.mock_dataflow,
            project_number=TEST_PROJECT,
            name="name-",
            location=TEST_LOCATION,
            poll_sleep=0,
            job_id=None,
            num_retries=20,
            multiple_jobs=True
        )
        result = dataflow_job.is_job_running()
        self.assertEqual(False, result)
    def test_dataflow_job_cancel_job(self):