Update embedding_model.py (#8836)

### What problem does this PR solve?

Remove useless covert for bge encode_queries

### Type of change

- [x] Performance Improvement

rag/llm/embedding_model.py

 
     def encode_queries(self, text: str):
         token_count = num_tokens_from_string(text)
-        return self._model.encode_queries([text]).tolist()[0], token_count
+        return self._model.encode_queries([text], convert_to_numpy=False)[0][0].cpu().numpy(), token_count
 
 
 class OpenAIEmbed(Base):