Update requests to use non-contextual entered spans #304
Description
The way our tracing support currently works is that we re-enter and exit a single span for each request which is passed around the system. This was really the only way of doing it previously, but conceptually doesn't really make sense since the request isn't starting and stopping, but rather ongoing until it completes. Based on tokio-rs/tracing#1252 it looks like it might be possible for us to change this soon.
See also tokio-rs/tracing#79.