tiny refactor: use ${CONTAINER_IFNAME} for name construction

weave

@@ -348,10 +348,10 @@ CONTAINER_NAME=${WEAVE_CONTAINER_NAME:-weave}
 BRIDGE=weave
 # This value is overridden when the datapath is used unbridged
 DATAPATH=datapath
-BRIDGE_IFNAME=vethwe-bridge
-DATAPATH_IFNAME=vethwe-datapath
-PCAP_IFNAME=vethwe-pcap
 CONTAINER_IFNAME=ethwe
+BRIDGE_IFNAME=v${CONTAINER_IFNAME}-bridge
+DATAPATH_IFNAME=v${CONTAINER_IFNAME}-datapath
+PCAP_IFNAME=v${CONTAINER_IFNAME}-pcap
 PORT=${WEAVE_PORT:-6783}
 HTTP_ADDR=${WEAVE_HTTP_ADDR:-127.0.0.1:6784}
 PROXY_PORT=12375