WELLESLEY, Mass. — A draft document on costs of fire alarm and sprinkler systems in Massachusetts could lead to a rollback in requirements in some multi-unit residential buildings, a group of concerned fire officials said Tuesday.About 40 fire officials attended a meeting of the Board of Building Regulations and Standards in Wellesley to oppose the draft white paper, which examines the cost and effectiveness of fire systems in buildings with three to six units.The board administers the state building code.