Tendermint uses the go-kit metrics library to create and register metrics.
Tendermint only uses the standard prometheus implementations of the various
go-kit metrics type. We therefore derive very little benefit from using the go-kit
types. It also prevents Tendermint from easily generating two instances of the nodeImpl
with metrics for each. This is because go-kit under the hood uses the DefaultRegistry
from prometheus which is a global object, created and managed by the prometheus
library. Migrating to use just prometheus will allow us to control and insantiate
separate metrics registries for each instance of the nodeImpl that is created.

• replace go-kit metrics with equivalent standard prometheus types
• node creation constructs prometheus registry