[lyon] fix geminis' ib1/2 mounted state

input/grid5000/sites/lyon/clusters/gemini/gemini_ib.yaml

@@ -8,12 +8,12 @@ nodes:
         netmask: 255.255.240.0
       ib1:
         enabled: true
-        mountable: true
-        mounted: true
+        mountable: false
+        mounted: false
       ib2:
         enabled: true
-        mountable: true
-        mounted: true
+        mountable: false
+        mounted: false
       ib3:
         enabled: false
         mountable: false