Environment definition contains cucim, but we don't need/use it

[ant0nsc]

Is there an existing issue for this?

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Bug summary

The default Linux environment file contains the cucim package. To the best of my knowledge, this is not required for any of the InnerEye functionality. Cucim is only used in the hi-ml-histopathology module, which we don't really use in InnerEye.
This leads to problems as reported by @kh296 in #741

Code for reproduction

See https://github.com/microsoft/InnerEye-DeepLearning/issues/741

Actual outcome

n/a

Error messages

No response

Expected outcome

Creating a Conda environment on a non-GPU machine should work just fine.

System info

No response

AB#6272