update the train_batch_size in case HPO change batch_size_per_device (#18918)

Signed-off-by: Wang, Yi A <yi.a.wang@intel.com>
Signed-off-by: Wang, Yi A <yi.a.wang@intel.com>

src/transformers/trainer.py

@@ -1488,6 +1488,7 @@ class Trainer:
             raise TypeError(f"train() received got unexpected keyword arguments: {', '.join(list(kwargs.keys()))}.")
         # This might change the seed so needs to run first.
         self._hp_search_setup(trial)
+        self._train_batch_size = self.args.train_batch_size
 
         # Model re-init
         model_reloaded = False