[TASK] Integrate tokio_metrics to dkg-gadget

[1xstj]

Task summary
We track a lot of chain related info using prometheus on the dkg-gadget, it would be helpful to integrate tokio_metrics and plug those values to the prometheus metrics aswell. This gives us visilibility on time for a thread to execute and also helps debugging failed or dropped threads.

Specification reference

• https://docs.rs/tokio-metrics/latest/tokio_metrics/struct.TaskMonitor.html