**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.


tests/providers/google/cloud/hooks/test_dataflow.py
#
#
#
#
import copy
import shlex
import unittest
from typing import Any, Dict
import mock
from mock import MagicMock
from parameterized import parameterized
from airflow.exceptions import AirflowException
from airflow.providers.google.cloud.hooks.dataflow import (
    DEFAULT_DATAFLOW_LOCATION, DataflowHook, DataflowJobStatus, DataflowJobType, _DataflowJobsController,
    _DataflowRunner, _fallback_to_project_id_from_variables,
)
TASK_ID = 'test-dataflow-operator'
JOB_NAME = 'test-dataflow-pipeline'
MOCK_UUID = '12345678'
UNIQUE_JOB_NAME = 'test-dataflow-pipeline-{}'.format(MOCK_UUID)
TEST_TEMPLATE = 'gs://dataflow-templates/wordcount/template_file'
PARAMETERS = {
    'inputFile': 'gs://dataflow-samples/shakespeare/kinglear.txt',
    'output': 'gs://test/output/my_output'
}
PY_FILE = 'apache_beam.examples.wordcount'
JAR_FILE = 'unitest.jar'
JOB_CLASS = 'com.example.UnitTest'