[Bug] Non -GPT model disable system prompt

[d4renk]

Describe the bug
A clear and concise description of what the bug is.
Self-deployed large models will automatically inject system-level prompts, resulting in incorrect answers.
It should be that only gpt api injects the default system prompt.
自部署大模型会默认注入系统提示 导致回答错误
应该是只有gpt api注入才对
#3684
这个pull似乎没有考虑到自部署大模型的情况
V2.10.1
To Reproduce
Steps to reproduce the behavior:

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2. Click on '....'
3. Scroll down to '....'
4. See error
   docker deployment and add environment variables.
   docker部署并添加环境变量

CUSTOM_MODELS=-all,+Balanced-g4t-offline,+Creative-g4t,+Balanced-g4t,+Precise-g4t,+Creative,+Balanced,+Precise,+Creative-g4t-offline,+Precise-g4t-offline,+Creative-offline,+Balanced-offline,+Precise-offline
BASE_URL=https://bingai.zklcdc.xyz
HIDE_USER_API_KEY=1

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots
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Deployment

• [y] Docker
• Vercel
• Server

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional Logs
Add any logs about the problem here.
{"messages":[{"role":"system","content":"\nYou are ChatGPT, a large language model trained by OpenAI.\nKnowledge cutoff: 2021-09\nCurrent model: Balanced-g4t-offline\nCurrent time: 2024/1/31 20:21:45\nLatex inline: $x^2$ \nLatex block: $$e=mc^2$$\n\n"},{"role":"user","content":"hi"}],"stream":true,"model":"Balanced-g4t-offline","temperature":0.5,"presence_penalty":0,"frequency_penalty":0,"top_p":1}

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Title: [Bug] Non -GPT model disable system prompt