Improve the logs integration with `tracing`

### Description

We make use of structured logging a lot using `tracing`, i.e. a lot of context of our log messages is captured in fields set either on the message or via a span. By default, the rendering of the message in the logs overview is therefore pretty useless because one needs to unfold each message to see the variables.

For our stderr logs, we use `tracing_subscriber::fmt` so our heads are used to parsing through logs in that format. To mimic this, we added a `before_log` hook that renders certain fields as `key=value` into the message. The code for that is here: https://github.com/firezone/firezone/blob/ac34635db891f1a57ea36e8754894f1cf4984143/rust/telemetry/src/lib.rs#L296-L321

I am not sure what the best path forward here is for improving this feature from the Sentry side. I just wanted to share this as feedback how we are using it :)