**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
"""
    Helper class with Dataflow job statuses.
    """
    JOB_STATE_DONE = "JOB_STATE_DONE"
    JOB_STATE_RUNNING = "JOB_STATE_RUNNING"
    JOB_STATE_FAILED = "JOB_STATE_FAILED"
    JOB_STATE_CANCELLED = "JOB_STATE_CANCELLED"
    JOB_STATE_PENDING = "JOB_STATE_PENDING"
    FAILED_END_STATES = {JOB_STATE_FAILED, JOB_STATE_CANCELLED}
    SUCCEEDED_END_STATES = {JOB_STATE_DONE}
    END_STATES = SUCCEEDED_END_STATES | FAILED_END_STATES
class DataflowJobType: