r/buffered_protocol: removed append entries latency histogram

We already track RPC methods latency so the histogram can be removed.

Signed-off-by: Michał Maślanka <michal@redpanda.com>

src/v/raft/buffered_protocol.cc

@@ -375,12 +375,7 @@ void append_entries_queue::setup_internal_metrics() {
          [this] { return _requests.size(); },
          sm::description(
            "Total number of append entries requests in the queue"),
-         {target_node_id_label}),
-       sm::make_histogram(
-         "append_entries_request_latency",
-         sm::description("Latency of append entries requests"),
-         {target_node_id_label},
-         [this] { return _hist.internal_histogram_logform(); })});
+         {target_node_id_label})});
 }
 
 void append_entries_queue::setup_public_metrics() {