support prometheus metrics out of the box

[Loki-Afro]

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name: Feature request
about: support prometheus metrics out of the box

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Is your feature request related to a problem? Please describe.
the current metrics endpoint returns json, that is not suitable for a prometheus scraper

Describe the solution you'd like
maybe replace node-measured with https://github.com/open-telemetry/opentelemetry-js which is actively maintained, maybe you know a better one ..

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.
node-measured appears to be dead for 4 years or more yaorg/node-measured#82

Plugin?
maybe? but then i think node-measured should still be removed as it appears to be dead