bundles/grafana: add "traffic per interface" graphs, fix naming of values

bundles/grafana/dashboard-rows/cpu.py

@@ -24,6 +24,11 @@ def dashboard_row_cpu(panel_id, node):
         r["_field"] == "usage_{measurement}" and
         r["host"] == "{node.name}"
     )
+    |> map(fn: (r) => ({{
+            r with
+            _field: "{measurement}"
+        }})
+    )
     |> aggregateWindow(every: v.windowPeriod, fn: mean, createEmpty: false)
     |> yield(name: "{measurement}")""",
             'resultFormat': 'time_series',