**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
)
        job_controller.wait_for_done()
    @_fallback_to_location_from_variables
    @_fallback_to_project_id_from_variables
    @GoogleBaseHook.fallback_to_default_project_id
    def start_java_dataflow(
        self,
        job_name: str,
        variables: Dict,
        jar: str,
        project_id: str,
        job_class: Optional[str] = None,
        append_job_name: bool = True,
        multiple_jobs: bool = False,
        on_new_job_id_callback: Optional[Callable[[str], None]] = None,
        location: str = DEFAULT_DATAFLOW_LOCATION
    ) -> None:
        """
        Starts Dataflow java job.
        :param job_name: The name of the job.
        :type job_name: str
        :param variables: Variables passed to the job.
        :type variables: dict
        :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.
        :param jar: Name of the jar for the job
        :type job_class: str
        :param job_class: Name of the java class for the job.
        :type job_class: str
        :param append_job_name: True if unique suffix has to be appended to job name.