[hotfix] disable koa http request logger except in dev env

• problem: the [app] logs are cluttered with loglines about GET requests to the metrics endpoint. these do not actually provide any useful information and obscure other actually useful information b/c they can't be deduped in "explore" mode
• observation: we don't actually need to log http traffic in the app container. this is already logged in the nginx container layer. if we really care to inspect that, we can look there.
• solution: ensure that we are exporing nginx proxy logs to loki, and then disable the default koa logger plugin whenever `NODE_ENV === 'production'