[Misc] Remove experimental dep from tracing.py

[codefromthecrypt]

Currently, the OpenTelemetry POC imports constants from a type that no longer exists. This copies the constants instead as is usually advised to prevent version locks.

This also finishes name conversion from llm -> gen_ai per upstream https://github.com/open-telemetry/semantic-conventions/blob/main/docs/gen-ai/gen-ai-spans.md

Fix #11993

[github-actions]

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[codefromthecrypt]

note: I left these alone, but some look like they are attributes or names of metrics, not spans. Perhaps double-check at some point if it is desired to capture these datapoints as span attributes vs metrics.

https://github.com/open-telemetry/semantic-conventions/blob/main/docs/gen-ai/gen-ai-metrics.md

[codefromthecrypt]

I think the failure is unrelated:

[2025-01-13T13:33:36Z] E           huggingface_hub.errors.HfHubHTTPError: 500 Server Error: Internal Server Error for url: https://huggingface.co/facebook/opt-125m/resolve/main/sentence_camembert_config.json (Request ID: Root=1-678514f3-7a782ba707c969e359375b92;ed6140ec-8e9a-40c9-ba03-bb46e895e54f)
--
  | [2025-01-13T13:33:36Z] E
  | [2025-01-13T13:33:36Z] E           The request is taking longer than expected, please try again later.

[DarkLight1337]

Sorry for the delay, I think @rkooo567 (who originally worked on this) is busy nowadays so he doesn't have time to review this. Your changes look good to me!