cleanup: address gomnd warnings

Direct usage of numbers should be avoided.

Issue reported:
mnd: Magic number: X, in <argument> detected (gomnd)

Signed-off-by: Yug <yuggupta27@gmail.com>

internal/journal/voljournal.go

@@ -401,7 +401,7 @@ func (conn *Connection) UndoReservation(ctx context.Context,
 
 	cj := conn.config
 	if volName != "" {
-		if len(volName) < 36 {
+		if len(volName) < uuidEncodedLength {
 			return fmt.Errorf("unable to parse UUID from %s, too short", volName)
 		}