Add metrics about local backend

[overvenus]

Feature Request

Is your feature request related to a problem? Please describe:

For now, there is no way to observe local backend via Grafana. It is helpful to debug an import failure if we can record errors and other information in metrics.

Describe the feature you'd like:

Add metrics about local backend.

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Optimization: