From dthayer's comment it appears as though we can be more pleasant during shutdown by:
- Starting our shutdown earlier during
- This should be an okay thing to do for our consumers who are already used to this being the final point in time that Telemetry can be recorded
- Blocking on our shutdown tasks completing during
This might be a little tricky given how the Rust Glean SDK currently exposes its shutdown, but we can change that (maybe leave
shutdown()'s timing as-is (only returns when shutdown is complete), but introduce a
begin_shutdown() which kicks things off and then returns immediately?).