Restore Jaeger tracer in dev

The large tower of dependency Jenga should have been resolved by scala-steward + mergify. scala-opentracing has cats / cats-effect 2.2 merged in `master` but not released, so I think that should be the last thing to restore it, but we might even be fine without that (since the big cats 2.2 change is getting rid of `cats.implicits._` everywhere)