chore: add LangGraph node_metrics isolation regression test #670

Job	Run time
server-ai-linux (3.10)	16s
server-ai-langchain-windows (3.13)	32s
server-ai-langchain-linux (3.14)	20s
server-ai-openai-linux (3.11)	32s
server-ai-langchain-linux (3.13)	23s
server-ai-openai-linux (3.13)	30s
server-ai-linux (3.13)	20s
server-ai-openai-windows (3.10)	26s
server-ai-openai-linux (3.10)	29s
server-ai-openai-linux (3.14)	26s
server-ai-linux (3.14)	16s
server-ai-windows (3.12)	22s
server-ai-langchain-windows (3.14)	30s
server-ai-openai-windows (3.12)	45s
server-ai-openai-windows (3.11)	21s
server-ai-optimization-windows (3.14)	19s
server-ai-optimization-windows (3.13)	47s
server-ai-langchain-windows (3.12)	36s
server-ai-openai-windows (3.14)	34s
server-ai-optimization-windows (3.10)	34s
server-ai-windows (3.14)	22s
server-ai-optimization-linux (3.10)	12s
server-ai-optimization-windows (3.11)	20s
server-ai-linux (3.11)	19s
server-ai-langchain-linux (3.12)	20s
server-ai-langchain-linux (3.11)	21s
server-ai-langchain-windows (3.11)	41s
server-ai-linux (3.12)	20s
server-ai-windows (3.10)	25s
server-ai-optimization-linux (3.11)	10s
server-ai-windows (3.11)	21s
server-ai-openai-windows (3.13)	9s
server-ai-langchain-windows (3.10)	26s
server-ai-optimization-linux (3.13)	11s
server-ai-optimization-windows (3.12)	19s
server-ai-langchain-linux (3.10)	22s
server-ai-optimization-linux (3.14)	11s
server-ai-openai-linux (3.12)	29s
server-ai-windows (3.13)	38s
server-ai-optimization-linux (3.12)	11s
	16m 5s

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