Rework logging (#3358)

Unified all log files into one.

### What problem does this PR solve?

Unified all log files into one.

### Type of change

- [x] Refactoring

rag/svr/discord_svr.py

@@ -17,6 +17,7 @@ import discord
 import requests
 import base64
 import asyncio
+from api.utils.log_utils import logger
 
 URL = '{YOUR_IP_ADDRESS:PORT}/v1/api/completion_aibotk' # Default: https://demo.ragflow.io/v1/api/completion_aibotk
 
@@ -36,7 +37,7 @@ client = discord.Client(intents=intents)
 
 @client.event
 async def on_ready():
-    print(f'We have logged in as {client.user}')
+    logger.info(f'We have logged in as {client.user}')
 
 
 @client.event