Restore the route_actual_response_total metric (#468)

339efa8 incorrectly removed the route_actual metrics scope from the
outbound stack. This change restores these metrics but omits latency
buckets from export.

Fixes linkerd/linkerd2#4215

Author: olix0r

linkerd/app/outbound/src/lib.rs

@@ -263,6 +263,7 @@ impl Config {
 
             let http_profile_route_proxy = svc::proxies()
                 .check_new_clone_service::<dst::Route>()
+                .push(metrics.http_route_actual.into_layer::<classify::Response>())
                 // Sets an optional retry policy.
                 .push(retry::layer(metrics.http_route_retry))
                 .check_new_clone_service::<dst::Route>()

linkerd/app/src/metrics.rs

@@ -48,7 +48,7 @@ impl Metrics {
                 .clone()
                 .into_report(retain_idle)
                 .with_prefix("route_actual");
-            (m, r)
+            (m, r.without_latencies())
         };
 
         let http_errors = errors::Metrics::default();