feat: If combining text and files, place the text prompt after the fi… (#24472)

api/core/workflow/nodes/llm/node.py

                 and isinstance(prompt_messages[-1], UserPromptMessage)
                 and isinstance(prompt_messages[-1].content, list)
             ):
-                prompt_messages[-1] = UserPromptMessage(content=prompt_messages[-1].content + file_prompts)
+                prompt_messages[-1] = UserPromptMessage(content=file_prompts + prompt_messages[-1].content)
             else:
                 prompt_messages.append(UserPromptMessage(content=file_prompts))