[sophia][servers] remove no more used servers

data/grid5000/sites/sophia/servers/srv-stock.json

-{
-  "kind": "physical",
-  "network_adapters": {
-    "adm": {
-      "ip": "172.17.143.3",
-      "mac": "00:22:19:63:cd:83",
-      "mounted": true
-    },
-    "bmc": {
-      "ip": "172.17.143.12",
-      "mac": "00:22:19:63:cd:8b",
-      "mounted": true
-    },
-    "default": {
-      "ip": "172.16.143.3",
-      "mac": "00:1b:21:48:d0:a1",
-      "mounted": true
-    }
-  },
-  "serial": "FVNSH4J",
-  "type": "server",
-  "uid": "srv-stock",
-  "warranty": "2016-02-10"
-}
\ No newline at end of file