**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.


airflow/providers/google/cloud/hooks/dataflow.py
project_id: str,
        location: str = DEFAULT_DATAFLOW_LOCATION,
        variables: Optional[Dict] = None
    ) -> bool:
        """
        Helper method to check if jos is still running in dataflow
        :param name: The name of the job.
        :type name: str
        :param project_id: Optional, the GCP project ID in which to start a job.
            If set to None or missing, the default project_id from the GCP connection is used.
        :type project_id: str
        :param location: Job location.
        :type location: str
        :return: True if job is running.
        :rtype: bool
        """
        if variables:
            warnings.warn(
                "The variables parameter has been deprecated. You should pass location using "
                "the location parameter.", DeprecationWarning, stacklevel=4)
        jobs_controller = _DataflowJobsController(
            dataflow=self.get_conn(),
            project_number=project_id,
            name=name,
            location=location,
            poll_sleep=self.poll_sleep
        )
        return jobs_controller.is_job_running()
    @GoogleBaseHook.fallback_to_default_project_id
    def cancel_job(