refactor: Remove unused code in large_language_model.py (#5433)

api/tests/integration_tests/model_runtime/cohere/test_llm.py

@@ -136,12 +136,6 @@ def test_invoke_chat_model():
     assert isinstance(result, LLMResult)
     assert len(result.message.content) > 0
 
-    for chunk in model._llm_result_to_stream(result):
-        assert isinstance(chunk, LLMResultChunk)
-        assert isinstance(chunk.delta, LLMResultChunkDelta)
-        assert isinstance(chunk.delta.message, AssistantPromptMessage)
-        assert len(chunk.delta.message.content) > 0 if chunk.delta.finish_reason is None else True
-
 
 def test_invoke_stream_chat_model():
     model = CohereLargeLanguageModel()