chore(vendor): sync OpenLLMetry fr-v0.52.6.27

[sayonfortify]

Vendors FortifyRoot OpenLLMetry tag fr-v0.52.6.27 into Ocelle.

This carries the LangChain streaming-latency span attribute support from FortifyRoot/openllmetry-py#38:

• fortifyroot.llm.streaming.time_to_first_token_ms on first LangChain on_llm_new_token
• fortifyroot.llm.streaming.time_to_generate_ms at on_llm_end when a first token was observed
• non-streaming/no-token calls keep the attrs absent

Vendoring followed the SOP: fork PR merged, tag created, then ./scripts/vendor.sh ../fr-openllmetry-py . fr-v0.52.6.27.

Local validation:

• fork modification notices check passed before vendoring
• python3 -m py_compile on changed vendored LangChain files
• /Users/sayondutta/opt/anaconda3/envs/py3.12/bin/python -m pip install -e .
• vendored import check: 34 passed
• full suite: 498 passed, 10 warnings
• git diff --check clean
• secret scan clean