Enabled test_sklearn.py, test_tensorflow.py, test_xgboost.py, test_transformer.py to run in an env without ext load balancer (#649)
Enabled test_sklearn.py, test_tensorflow.py, test_xgboost.py, test_transformer.py to run in an env without ext load balancer (#649)


kubeflow/kfserving-lts,kubeflow/kfserving-lts,kubeflow/kfserving-lts,kubeflow/kfserving-lts,kubeflow/kfserving-lts,kubeflow/kfserving-lts