chore: Skip unnecessary conversion of training dataset object passed into Tunings.tune()

PiperOrigin-RevId: 822609104

Author: speedstorm1

google/genai/tunings.py

@@ -248,12 +248,8 @@ def _CreateTuningJobParametersPrivate_to_vertex(
  setv(to_object, ['preTunedModel'], getv(from_object, ['pre_tuned_model']))
 
  if getv(from_object, ['training_dataset']) is not None:
- setv(
- to_object,
- ['supervisedTuningSpec', 'trainingDatasetUri'],
- _TuningDataset_to_vertex(
- getv(from_object, ['training_dataset']), to_object, root_object
- ),
+ _TuningDataset_to_vertex(
+ getv(from_object, ['training_dataset']), to_object, root_object
  )
 
  if getv(from_object, ['config']) is not None: