TAIPEI, TAIWAN — Taiwan President Tsai Ing-wen has stepped down as head of her ruling party after it suffered defeat in Saturday’s local elections, while the Beijing-friendly main opposition held its ground. “The election results were not as expected…. I should shoulder all the responsibility and I resign as DPP chairwoman immediately,” Tsai, who will stay on as president of the self-ruled island, told reporters. Voters turned out Saturday to cast ballots for mayors, magistrates and various other posts in 22 cities and counties, while there was also a referendum on whether to lower the voting age from 20 to…