[nancy][wattmetre] Change alias IP of gros-wattmetre following swap adress IP between srv and srv3

data/grid5000/sites/nancy/pdus/gros-wattmetre1.json

 {
-  "ip": "172.16.79.18",
+  "ip": "172.16.79.15",
   "metrics": [
     {
       "description": "Power consumption per outlet reported by wattmetre, in watt",

data/grid5000/sites/nancy/pdus/gros-wattmetre2.json

 {
-  "ip": "172.16.79.18",
+  "ip": "172.16.79.15",
   "metrics": [
     {
       "description": "Power consumption per outlet reported by wattmetre, in watt",

data/grid5000/sites/nancy/pdus/gros-wattmetre3.json

 {
-  "ip": "172.16.79.18",
+  "ip": "172.16.79.15",
   "metrics": [
     {
       "description": "Power consumption per outlet reported by wattmetre, in watt",

input/grid5000/sites/nancy/pdus.yaml

@@ -222,7 +222,7 @@ pdus:
   gros-wattmetre1:
     vendor: OmegaWatt
     model: ''
-    ip: 172.16.79.18
+    ip: 172.16.79.15
     sensors:
       - power:
           resolution: 1
@@ -243,7 +243,7 @@ pdus:
   gros-wattmetre2:
     vendor: OmegaWatt
     model: ''
-    ip: 172.16.79.18
+    ip: 172.16.79.15
     sensors:
       - power:
           resolution: 1
@@ -264,7 +264,7 @@ pdus:
   gros-wattmetre3:
     vendor: OmegaWatt
     model: ''
-    ip: 172.16.79.18
+    ip: 172.16.79.15
     sensors:
       - power:
           resolution: 1