Fix akka dispather filter

[liguobin233]

As the documentation says, the content of the dispatcher filter have an actorSystem prefix

kamon.instrumentation.akka.filters {

  actors.track {
    includes = [ "my-app/user/job-manager", "my-app/user/worker-*" ]
    excludes = [ "my-app/system/**", "my-app/user/worker-helper" ]
  }

  dispatchers {
    includes = [ "my-app/akka.actor.default-dispatcher" ]
  }

  routers {
    includes = [ "my-app/user/some-router" ]
  }
}