feat: move detected field logic to query frontend

[loki-gh-app]

Backport 36ace66 from #14212

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What this PR does / why we need it:

/detected_fields queries in ops are failing over bigger time ranges in Explore Logs, whereas logs queries for the same time period are not. I think this is because of all the optimizations/protections we have in place for logs queries (result cache, sharding, limits, etc.) that have not been implemented for /detected_fields. However, since /detected_fields is just doing a SelectLogs under the hood in the querier, if we move the detected fields logic up to the Query Frontend we can use the existing limited and filter tripperwares to get the underlying logs. Due to the limits already in place in those tripperwares, they will never return too many lines for the detected fields logic to reasonably handle in the Query Frontend, which allows us to move this logic there without fear of knocking over QFs.

This replaces #14210 as it works much better. I have tested in in Ops and it solves the problem without overloading QFs.

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
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