prometheus: Update router edge traffic variables

The node_exporter 0.16.0 release broke a bunch of network metric
names (e.g. [1]), arguably for good reasons, but still.

1. prometheus/node_exporter#830

house/nomad/conf/prometheus/node.rules

@@ -28,9 +28,9 @@ groups:
   - name: node_router
     rules:
     - record: router:edge:receive_bytes
-      expr: node_network_receive_bytes{device="eth0",host="router"}
+      expr: node_network_receive_bytes_total{device="eth0",host="router"}
     - record: router:edge:transmit_bytes
-      expr: node_network_transmit_bytes{device="eth0",host="router"}
+      expr: node_network_transmit_bytes_total{device="eth0",host="router"}
     - record: router:edge:receive_bytes:rate5m
       expr: rate(router:edge:receive_bytes[5m])
     - record: router:edge:transmit_bytes:rate5m