Make the host tag on emitted metrics optional, and drop the unused logger metrics

Make the host tag on emitted metrics optional, and drop the unused logger metrics: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). Right now every metric the gateway emits ends up with a host tag (the hostname of the machine running the process). For a large fleet…