**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/operators/test_dataflow.py
def setUp(self):
        self.dataflow = DataflowTemplatedJobStartOperator(
            task_id=TASK_ID,
            template=TEMPLATE,
            job_name=JOB_NAME,
            parameters=PARAMETERS,
            options=DEFAULT_OPTIONS_TEMPLATE,
            dataflow_default_options={"EXTRA_OPTION": "TEST_A"},
            poll_sleep=POLL_SLEEP,
            location=TEST_LOCATION
        )
    @mock.patch('airflow.providers.google.cloud.operators.dataflow.DataflowHook')
    def test_exec(self, dataflow_mock):