Kale couldn't use current notebook image if there are multiple containers in the pod

[akrava]

I've got latest version of Kale extension in the jupyterhub notebook. The pod of the my botebook has got two containers: app and istio-proxy. When I launch pipeline I see that current notebook image is not used. Here is the logs:

2022-07-15 11:02:41 run:83 [[DEBUG]] [TID=dqxkq9qwb0] [] Decoding ctx of RPC function 'nb.get_base_image'
2022-07-15 11:02:41 run:95 [[DEBUG]] [TID=dqxkq9qwb0] [/home/dev1/candies_sharing.ipynb] Decoding kwargs of RPC function 'nb.get_base_image'
2022-07-15 11:02:41 run:104 [[DEBUG]] [TID=dqxkq9qwb0] [/home/dev1/candies_sharing.ipynb] Importing RPC function 'nb.get_base_image'
2022-07-15 11:02:41 run:113 [[INFO]] [TID=dqxkq9qwb0] [/home/dev1/candies_sharing.ipynb] Executing RPC function 'get_base_image()'
2022-07-15 11:02:41 run:124 [[ERROR]] [TID=dqxkq9qwb0] [/home/dev1/candies_sharing.ipynb] RPC function 'get_base_image' raised an unhandled exception
Traceback (most recent call last):
  File "/opt/miniconda/lib/python3.8/site-packages/kale/rpc/run.py", line 116, in run
    result = func(request, **kwargs)
  File "/opt/miniconda/lib/python3.8/site-packages/kale/rpc/nb.py", line 87, in get_base_image
    return podutils.get_docker_base_image()
  File "/opt/miniconda/lib/python3.8/site-packages/kale/common/podutils.py", line 272, in get_docker_base_image
    container_name = get_container_name()
  File "/opt/miniconda/lib/python3.8/site-packages/kale/common/podutils.py", line 136, in get_container_name
    raise RuntimeError("No container names left. Could not infer the name"
RuntimeError: No container names left. Could not infer the name of the running container.

[akrava]

In this block of code https://github.com/kubeflow-kale/kale/blob/master/backend/kale/common/podutils.py#L114-L125 I've found a typo in the if statement:

    if len(candidates) > 0:
        raise RuntimeError("No container names left. Could not infer the name"
                           " of the running container.")

It should be if len(candidates) == 0: I guess.

That's why I've created PR in order to fix it: #435