[CherryPick][Serve][Doc] Update metrics & log doc (#34222)

[sihanwang41]

Update the logging & metrics for the 2.4. change.

Why are these changes needed?

cherrypick: #34222

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[akshay-anyscale]

Do we also need to update list of metrics here - https://docs.ray.io/en/latest/serve/production-guide/monitoring.html#built-in-ray-serve-metrics

[sihanwang41]

Do we also need to update list of metrics here - https://docs.ray.io/en/latest/serve/production-guide/monitoring.html#built-in-ray-serve-metrics

You are checking the 2.3.1, it is already updated in the 2.4.0 doc. https://anyscale-ray--34326.com.readthedocs.build/en/34326/serve/production-guide/monitoring.html

[sihanwang41]

tests failures are not related.

[sihanwang41]

ping @zhe-thoughts ^^

[jjyao]

I'll merge after releasing to pypi