Revert "[nantes/econome] econome-15 had a rate on a unmouted interface"

This reverts commit fd05d15d.

data/grid5000/sites/nantes/clusters/econome/nodes/econome-15.json

@@ -120,6 +120,7 @@
       "mountable": false,
       "mounted": false,
       "name": "eno1",
+      "rate": 1000000000,
       "sriov": true,
       "sriov_totalvfs": 7,
       "vendor": "Intel"

input/grid5000/sites/nantes/clusters/econome/nodes/econome-15.yaml

@@ -55,6 +55,7 @@ econome-15:
       management: false
       model: I350 Gigabit Network Connection
       name: eno1
+      rate: 1000000000
       sriov: true
       sriov_totalvfs: 7
       vendor: Intel