[Tests, GPU, SLOW] fix a bunch of GPU hardcoded tests in Pytorch (#4468)

* fix gpu slow tests in pytorch

* change model to device syntax

tests/test_modeling_encoder_decoder.py

@@ -329,5 +329,5 @@ class EncoderDecoderModelTest(unittest.TestCase):
 
     @slow
     def test_real_bert_model_from_pretrained(self):
-        model = EncoderDecoderModel.from_pretrained("bert-base-uncased", "bert-base-uncased")
+        model = EncoderDecoderModel.from_encoder_decoder_pretrained("bert-base-uncased", "bert-base-uncased")
         self.assertIsNotNone(model)