[Refactor] Lazy-loaded reasoning_parser (#28092)

Signed-off-by: chaunceyjiang <chaunceyjiang@gmail.com>

vllm/reasoning/mistral_reasoning_parser.py

@@ -4,14 +4,13 @@
 from functools import cached_property
 
 from vllm.logger import init_logger
-from vllm.reasoning import ReasoningParser, ReasoningParserManager
+from vllm.reasoning import ReasoningParser
 from vllm.reasoning.deepseek_r1_reasoning_parser import DeepSeekR1ReasoningParser
 from vllm.transformers_utils.tokenizers.mistral import MistralTokenizer
 
 logger = init_logger(__name__)
 
 
-@ReasoningParserManager.register_module("mistral")
 class MistralReasoningParser(DeepSeekR1ReasoningParser):
     """
     Reasoning parser for Mistral models.