In tents in the stifling heat and in bombed-out mosques, Gazans marked Sunday the start of the Muslim holiday of Eid al-Adha, devoid of the usual cheer as the Israel-Hamas war raged on. “There is no joy. We have been robbed of it,” said Malakiya Salman, a 57-year-old displaced woman, now living in a tent in Khan Yunis city in the southern Gaza Strip. Gazans, like Muslims the world over, would usually slaughter sheep for the holiday — whose Arabic name means “feast of the sacrifice” — and share the meat with the needy. Parents would also gift children new clothes and money in celebration. But…