Changed from:
- gnmic_interfaces_interface_state_counters_out_octets
- gnmic_interfaces_interface_state_counters_in_octets
- target label
To:
- gnmic_interfaces_out_octets
- gnmic_interfaces_in_octets
- source label
These match the actual metrics generated by gNMIc with the simplified
/interfaces/interface/state path and trim-prefixes processor.
