SAN DIEGO — Two former San Diego city attorneys have followed through on their threat from last week and filed a lawsuit against the National Football League and its 32 team owners, accusing them of violating their own rules governing team relocations. The legal complaint was filed by former San Diego City Attorney Michael Aguirre and his law partner and former deputy Maria Severson. It accuses league and team officials of failing to negotiate in good faith over more than 10 years, while city officials worked to find a new playing field for the San Diego Chargers or to upgrade the team’s longt…