[#1236] cli: Fix netinfo output for empty unknown parameters

Signed-off-by: Alexander Chuprov <a.chuprov@yadro.com>

cmd/frostfs-cli/modules/netmap/netinfo.go

@@ -50,8 +50,12 @@ var netInfoCmd = &cobra.Command{
 		cmd.Printf(format, "Maintenance mode allowed", netInfo.MaintenanceModeAllowed())
 
 		cmd.Println("FrostFS network configuration (other)")
-		netInfo.IterateRawNetworkParameters(func(name string, value []byte) {
-			cmd.Printf(format, name, hex.EncodeToString(value))
+		netInfo.IterateRawNetworkParameters(func(name string, rawValue []byte) {
+			value := hex.EncodeToString(rawValue)
+			if value == "" {
+				value = `""`
+			}
+			cmd.Printf(format, name, value)
 		})
 	},
 }