By Per Ake Persson Spanish all-time great Javier Castillejo, 40, comes back April 4 in the big indoor bullfighting arena in Leganes against compatriot Pablo Navascues. Castillejo, 62-8-0-1 and a world champ at both junior middle and middleweight, comes off a bad KO loss to Sebastian Sylvester last year and is at the crossroads of…