**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 types.
    """
    JOB_TYPE_UNKNOWN = "JOB_TYPE_UNKNOWN"
    JOB_TYPE_BATCH = "JOB_TYPE_BATCH"
    JOB_TYPE_STREAMING = "JOB_TYPE_STREAMING"
class _DataflowJobsController(LoggingMixin):
    """
    Interface for communication with Google API.
    It's not use Apache Beam, but only Google Dataflow API.
    :param dataflow: Discovery resource
    :param project_number: The Google Cloud Platform Project ID.
    :param location: Job location.
    :param poll_sleep: The status refresh rate for pending operations.
    :param name: The Job ID prefix used when the multiple_jobs option is passed is set to True.
    :param job_id: ID of a single job.
    :param num_retries: Maximum number of retries in case of connection problems.
    :param multiple_jobs: If set to true this task will be searched by name prefix (``name`` parameter),
        not by specific job ID, then actions will be performed on all matching jobs.
    """
    def __init__(