**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/operators/dataflow.py
self, *,
            template: str,
            job_name: str = '{{task.task_id}}',
            options: Optional[Dict[str, Any]] = None,
            dataflow_default_options: Optional[Dict[str, Any]] = None,
            parameters: Optional[Dict[str, str]] = None,
            project_id: Optional[str] = None,
            location: str = DEFAULT_DATAFLOW_LOCATION,
            gcp_conn_id: str = 'google_cloud_default',
            delegate_to: Optional[str] = None,
            poll_sleep: int = 10,
            **kwargs) -> None:
        super().__init__(**kwargs)
        self.template = template
        self.job_name = job_name
        self.options = options or {}
        self.dataflow_default_options = dataflow_default_options or {}
        self.parameters = parameters or {}
        self.project_id = project_id
        self.location = location
        self.gcp_conn_id = gcp_conn_id
        self.delegate_to = delegate_to
        self.poll_sleep = poll_sleep
        self.job_id = None
        self.hook: Optional[DataflowHook] = None
    def execute(self, context):