Potential Metrics Renaming

[travisby]

Hello!

I was perusing the otel documentation, and found they actually have semantic conventions for common metric names.

I don't personally love the name format (or really, the attribute format. The tags don't seem to perfectly fit river with its job kinds), but offering it as an FYI incase this is something the river team would like to take on for the existing metrics!

https://opentelemetry.io/docs/specs/semconv/messaging/messaging-metrics/

[brandur]

Hey @travisby, yeah I guess given it's an OpenTelemetry convention, it seems like a good idea to put these extra metrics in, although personally I'd have a stronger preference for more customized, descriptive metrics that are specific to the messaging queue. I think what I'll do is add these, but put them behind a configuration flag so we're not double emitting a bunch of metrics by default. Thanks for the heads up.

I opened #10 for an unrelated change which has a bunch of refactoring in it that'll conflict with the change proposed here, but I'll implement this after that's safely in master.