text: Title: Replace `go mock` with `client-go fake client` in unit tests
  Body: ### What you would like to be added?
  
  `go mock` should be replaced with `client-go fake client` in unit tests.
  
  
  ### Why is this needed?
  
  Reference: https://github.com/kubeflow/katib/pull/2289#discussion_r1718769690
  
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