Do not pass validation set and metrics callback to Image Classification API. (#4430)

* Do not pass validation set to Image Classification API.

* remove metric callback since it is set to default in ImageClassification Trainer.

Author: codemzs

src/Microsoft.ML.AutoML/TrainerExtensions/MultiTrainerExtensions.cs

@@ -240,9 +240,6 @@ public ITrainerEstimator CreateInstance(MLContext mlContext, IEnumerable<Sweepab
             ColumnInformation columnInfo, IDataView validationSet)
         {
             var options = TrainerExtensionUtil.CreateOptions<Options>(null, columnInfo.LabelColumnName);
-            options.ValidationSet = validationSet;
-            var logger = ((IChannelProvider)mlContext).Start(nameof(ImageClassificationExtension));
-            options.MetricsCallback = (ImageClassificationMetrics metric) => { logger.Trace(metric.ToString()); } ;
             return mlContext.MulticlassClassification.Trainers.ImageClassification(options);
         }