[1/2/N] Enable pymarkdown and python __init__ for lint system (#2011)

### What this PR does / why we need it?
1. Enable pymarkdown check
2. Enable python `__init__.py` check for vllm and vllm-ascend
3. Make clean code

### How was this patch tested?


- vLLM version: v0.9.2
- vLLM main:
29c6fbe58c

---------

Signed-off-by: wangli <wangli858794774@gmail.com>

docs/source/tutorials/single_npu_multimodal.md

@@ -191,4 +191,4 @@ Logs of the vllm server:
 INFO 03-12 11:16:50 logger.py:39] Received request chatcmpl-92148a41eca64b6d82d3d7cfa5723aeb: prompt: '<|im_start|>system\nYou are a helpful assistant.<|im_end|>\n<|im_start|>user\n<|vision_start|><|image_pad|><|vision_end|>\nWhat is the text in the illustrate?<|im_end|>\n<|im_start|>assistant\n', params: SamplingParams(n=1, presence_penalty=0.0, frequency_penalty=0.0, repetition_penalty=1.0, temperature=1.0, top_p=1.0, top_k=-1, min_p=0.0, seed=None, stop=[], stop_token_ids=[], bad_words=[], include_stop_str_in_output=False, ignore_eos=False, max_tokens=16353, min_tokens=0, logprobs=None, prompt_logprobs=None, skip_special_tokens=True, spaces_between_special_tokens=True, truncate_prompt_tokens=None, guided_decoding=None), prompt_token_ids: None, lora_request: None, prompt_adapter_request: None.
 INFO 03-12 11:16:50 engine.py:280] Added request chatcmpl-92148a41eca64b6d82d3d7cfa5723aeb.
 INFO:     127.0.0.1:54004 - "POST /v1/chat/completions HTTP/1.1" 200 OK
-```
+```