text: Title: [SDK] `objective_metric_name` to be required
  Body: ### What you would like to be added?
  
  ref: https://github.com/kubeflow/website/pull/3952#discussion_r1912197342
  
  ### Why is this needed?
  
  TODO
  
  ### Love this feature?
  
  Give it a 👍 We prioritize the features with most 👍