2.3.8: Improve witness metric (#51)
Added new metric to better capture failing extrinsic -> we parse the inner error through the metadata and use that as label such that we can differentiate where the error is coming from instead of having the general error system.extrinsicFailed
Added new metric for failing witnesses such that we can use these two new metrics to print the list of failing validators in our alerting system.
Improved witnessing metric for chaintracking -> in case of a very low number of witnesses we check also the previous epoch and use the sum of the two as the total. This will allow us to avoid alerting on false positive after a rotation.