Jean Franco, Lowell’s schools superintendent, will be choosing a new Lowell High School headmaster in the coming weeks, and at least one candidate is a familiar name throughout the city. Former mayor and city manager Brian Martin, 62, is putting his hat in the ring with full approval from his current employer, US Representative Niki Tsongas. Martin has worked as Tsongas’s district director and senior advisor on economic development for the past seven years. The current Lowell High headmaster, Ed Rozmiarek, is leaving his post when his contract expires June 30; Franco chose not to renew the contract. The position was posted on Feb. 8, and will close to candidates on March 8.