B #6607: Fix size of restored disk from backup (#3210)

(cherry picked from commit 420162da67)

src/datastore_mad/remotes/restic/stat

@@ -111,7 +111,7 @@ if !disk
     exit(-1)
 end
 
-size = disk.elements['//SIZE']
+size = disk.elements['SIZE']
 
 if !size
     STDERR.puts "Cannot find size for disk #{diskid[1]} in VM backup info"

src/datastore_mad/remotes/rsync/stat

@@ -117,7 +117,7 @@ if !disk
     exit(-1)
 end
 
-size = disk.elements['//SIZE']
+size = disk.elements['SIZE']
 
 if !size
     STDERR.puts "Cannot find size for disk  #{diskid[1]} in VM backup info"