when _validate_request, remove request_id, or error will like Unexpec…

[sywangyi]

…ted keys in the request: {'request_id'} INFO: ::1:44814 - "POST /v1/chat/completions HTTP/1.1" 422 Unprocessable Entity

What does this PR do?

Fixes # (issue)

@gante please review the PR.

how to produce the issue
transformers serve --log_level debug

transformers chat Qwen/Qwen2.5-0.5B-Instruct do_sample=False max_new_tokens=10

send 1st request-> OK
send 2st request->crash. client log:

File "/home/ywan171/transformers/src/transformers/commands/chat.py", line 742, in _inner_run
model_output, request_id = await interface.stream_output(stream)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ywan171/transformers/src/transformers/commands/chat.py", line 130, in stream_output
async for token in await stream:
^^^^^^^^^^^^
File "/workspace/ywan171/miniforge3/envs/optimum-intel/lib/python3.11/site-packages/huggingface_hub/inference/_generated/_async_client.py", line 963, in chat_completion
data = await self._inner_post(request_parameters, stream=stream)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/workspace/ywan171/miniforge3/envs/optimum-intel/lib/python3.11/site-packages/huggingface_hub/inference/_generated/_async_client.py", line 289, in _inner_post
raise error
File "/workspace/ywan171/miniforge3/envs/optimum-intel/lib/python3.11/site-packages/huggingface_hub/inference/_generated/_async_client.py", line 275, in _inner_post
response.raise_for_status()
File "/workspace/ywan171/miniforge3/envs/optimum-intel/lib/python3.11/site-packages/aiohttp/client_reqrep.py", line 1161, in raise_for_status
raise ClientResponseError(
aiohttp.client_exceptions.ClientResponseError: 422, message='Unprocessable Entity', url='http://localhost:8000/v1/chat/completions'

server log:
INFO: ::1:51300 - "POST /v1/chat/completions HTTP/1.1" 200 OK
Validating request: {'model': 'Qwen/Qwen2.5-0.5B-Instruct@main', 'stream': True, 'request_id': 'req_0', 'generation_config': '{\n "bos_token_id": 151643,\n "eos_token_id": [\n 151645,\n 151643\n ],\n "max_new_tokens": 10,\n "pad_token_id": 151643,\n "repetition_penalty": 1.1,\n "temperature": 0.7,\n "top_k": 20,\n "top_p": 0.8,\n "transformers_version": "4.56.0.dev0"\n}\n', 'messages': [{'role': 'user', 'content': 'hi'}, {'role': 'assistant', 'content': 'Hello! How can I assist you today? If'}, {'role': 'user', 'content': 'hi'}]}
Unexpected keys in the request: {'request_id'}
INFO: ::1:39042 - "POST /v1/chat/completions HTTP/1.1" 422 Unprocessable Entity

[sywangyi]

fixed by #40501