**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
command = [
            "--runner=DataflowRunner",
            "--project={}".format(project_id),
        ]
        if variables is None:
            return command
        
        
        
        for attr, value in variables.items():
            if attr == 'labels':
                command += label_formatter(value)
            elif value is None:
                command.append(f"--{attr}")
            elif isinstance(value, bool) and value:
                command.append(f"--{attr}")
            elif isinstance(value, list):
                command.extend([f"--{attr}={v}" for v in value])
            else:
                command.append(f"--{attr}={value}")
        return command
    @_fallback_to_location_from_variables
    @_fallback_to_project_id_from_variables
    @GoogleBaseHook.fallback_to_default_project_id
    def is_job_dataflow_running(
        self,
        name: str,