Fixed RAG script which was failing on dummy example (#21416)

* do not use prefix="val" for test

The dummy example fails when test_epoch_end is called. The prefix="test" should be dynamic in the log metrics too.

* Create test.source

* Create test.target

examples/research_projects/rag-end2end-retriever/finetune_rag.py

@@ -408,11 +408,11 @@ class GenerativeQAModule(BaseTransformer):
         self.save_metrics(metrics, prefix)  # writes to self.metrics_save_path
 
         log_dict = {
-            "val_avg_em": metrics["val_avg_em"],
+            f"{prefix}_avg_em": metrics[f"{prefix}_avg_em"],
             "step_count": metrics["step_count"],
-            "val_avg_loss": metrics["val_avg_loss"],
-            "val_loss": loss,
-            "val_em": metrics_tensor,
+            f"{prefix}_avg_loss": metrics[f"{prefix}_avg_loss"],
+            f"{prefix}_loss": loss,
+            f"{prefix}_em": metrics_tensor,
         }
         self.log_dict(log_dict)
 

examples/research_projects/rag-end2end-retriever/test_run/dummy-train-data/test.source

+What does Moses' rod turn into ?
+Who is Aron?
+Where did Moses grow up ?
+What happens at the command of the Moses ?
+Who manages the Pokémon ?
+Who owned the Pokémon trademark ?
+What else include in Pokémon franchise ?
+How many seasons in Pokémon animme series ?

examples/research_projects/rag-end2end-retriever/test_run/dummy-train-data/test.target

+to a snake
+Moses' assistant
+Egyptian royal court
+let his rod turn in to a snake
+The Pokémon Company
+Nintendo
+world's top-selling toy brand, the top-selling trading card game
+over 20 seasons