Brockton Mayor Robert Sullivan, who serves as chair of the school committee, said he forwarded the request to the governor on Friday, even though he opposed it. BROCKTON, Mass. — Officials have asked Gov. Maura Healey to send in the Massachusetts National Guard to stop violence and address security concerns at a troubled high school in a city south of Boston, some school committee members said Monday. Garff MHK Daphne Caine, who is a former children’s champion, will take on the role with immediate effect, he said. There are now 7.5 million borrowers enrolled in the SAVE Plan, of whom…