**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
self.dataflow_hook.cancel_job(
            job_name=UNIQUE_JOB_NAME,
            job_id=TEST_JOB_ID,
            project_id=TEST_PROJECT,
            location=TEST_LOCATION
        )
        jobs_controller.assert_called_once_with(
            dataflow=mock_get_conn.return_value,
            job_id=TEST_JOB_ID,
            location=TEST_LOCATION,
            name=UNIQUE_JOB_NAME,
            poll_sleep=10,
            project_number=TEST_PROJECT
        )
        jobs_controller.cancel()
class TestDataflowJob(unittest.TestCase):
    def setUp(self):
        self.mock_dataflow = MagicMock()
    def test_dataflow_job_init_with_job_id(self):
        mock_jobs = MagicMock()
        self.mock_dataflow.projects.return_value.locations.return_value. \
            jobs.return_value = mock_jobs
        _DataflowJobsController(
            self.mock_dataflow, TEST_PROJECT,
            TEST_LOCATION, 10, UNIQUE_JOB_NAME, TEST_JOB_ID).get_jobs()
        mock_jobs.get.assert_called_once_with(projectId=TEST_PROJECT, location=TEST_LOCATION,
                                              jobId=TEST_JOB_ID)
    def test_dataflow_job_init_without_job_id(self):