[sophia][bug_16616] modification of virtual.yaml : syntax adm: vs admin:,...

[sophia][bug_16616] modification of virtual.yaml : syntax adm: vs admin:, remove adm: intercace delaration when not necessary, add alias to align with other sites

data/grid5000/sites/sophia/servers/api-proxy.json

 {
   "kind": "virtual",
   "network_adapters": {
-    "admin": {
-      "ip": "172.17.143.111"
-    },
     "default": {
       "ip": "172.16.143.111"
     }