Actuator: support running multiple MetricsServices (aka consul/hystrix prevents dropwizard from loading) #5768
Description
I encountered a curious behavior where when I included spring-cloud-starter-consul-discovery, my dropwizard metrics did not work. This is because the consul module required hystrix, which required servo, which loaded before MetricsDropwizardAutoConfiguration, and therefore prevented it from loading since there was already a bean of CounterService.class and GuageService.class loaded.
All the interfaces in actuator seems to assume only one Counter/Gauge service is available. Instead it would be good to have a Counter/Guage registry and dispatch to all active Counter/Gauge services, so I can use features like hystrix/consul without preventing me from using the metrics library of my choice as well.