By Vivian Sequera, Mayela Armas and Deisy Buitrago CARACAS (Reuters) -Venezuela’s Supreme Justice Tribunal on Friday upheld a ban which prevents presidential candidate Maria Corina Machado from holding office, upending the opposition’s plans for elections planned later this year. With its ruling, Venezuela’s top court has barred Machado, a 56-year-old industrial engineer, from registering her candidacy for presidential elections scheduled for the second half of 2024. The decision came hours after three of Machado’s allies were detained on accusations of conspiracy, amid growing tensions betwee…