Param "response" is not used any more in python-senlinclient/senlinclient/tests/unit/v1/test_build_info.py

This issue exists on master branch under
python-senlinclient/senlinclient/tests/unit/v1/test_build_info.py

In class TestBuildInfo(fakes.TestClusteringv1), the following map is not used any more:
    response = {"build_info": {
    }}

It was replaced by "fake_bi":
        fake_bi = mock.Mock(
            api={"revision": "1.0"},
            engine={"revision": "1.0"}
        )

So, we can safely delete "response" from the code to keep it clean.