MRF: Better detection of non stable disks (#12252)

MRF does not detect when a node is disconnected and reconnected quickly
this change will ensure that MRF is alerted by comparing the last disk
reconnection timestamp with the last MRF check time.

Signed-off-by: Anis Elleuch <anis@min.io>

Co-authored-by: Klaus Post <klauspost@gmail.com>

cmd/xl-storage.go

@@ -335,6 +335,10 @@ func (s *xlStorage) IsOnline() bool {
 	return true
 }
 
+func (s *xlStorage) LastConn() time.Time {
+	return time.Time{}
+}
+
 func (s *xlStorage) IsLocal() bool {
 	return true
 }