Expose size stats in the UI

[matyax]

Use case: Logs Volume and the tab/panels titles communicate information about the amount of logs matching the current filters, but it doesn't say anything about the approximate size of the scanned data, which we get from the stats endpoint.

We should find a place for it in the UI and expose it in the same way it's done in Explore.

This shouldn't be interpreted as consumption/usage information.

[gtk-grafana]

#1482

[matyax]

Clarifying that this issue is about the /stats for the current query, analog to the query editor in Explore.

[gtk-grafana]

Which query? Volume or logs panel? Breakdowns? Service selection log panels and time series?

The bytes processed on the logs panel is an order of magnitude lower then any of the time series calls, so showing the logs stats will lead users to have very different expectations on query usage then the actual.

[matyax]

Right, because this issue is not about usage or consumption, but about volume accessed by the current query, being the current query the one that produces the logs, and the one that produces the metrics for Logs volume.

[matyax]

In any case, it's a great point to make sure that this (should it be implemented) must not confuse users with consumption or query usage.