reactor: advertise the logging_failures metric as a DERIVE counter
reactor: advertise the logging_failures metric as a DERIVE counter

Since it is under total_operations, it must be of type DERIVE.  Prometheus
checks it and gets confused.

avikivity/seastar,syuu1228/seastar,scylladb/seastar,dreamsxin/seastar,kjniemi/seastar,cloudius-systems/seastar,syuu1228/seastar,avikivity/seastar,dreamsxin/seastar,syuu1228/seastar,scylladb/seastar,cloudius-systems/seastar,scylladb/seastar,cloudius-systems/seastar,dreamsxin/seastar,kjniemi/seastar,avikivity/seastar,kjniemi/seastar