text: Title: Deprecate Skopt Suggestion Service
  Body: /kind feature
  
  **Describe the solution you'd like**
  [A clear and concise description of what you want to happen.]
  Unfortunately, the scikit-optimize was closed on February 29, 2024.
  
  https://github.com/scikit-optimize/scikit-optimize
  
  So we need to stop supporting the skopt suggestion service as well.
  I think that we can follow similar deprecation steps as the [MXNet](https://github.com/kubeflow/training-operator/issues/1996).
  
  **Anything else you would like to add:**
  [Miscellaneous information that will assist in solving the issue.]
  
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