SYDNEY — One of Australia’s top writers’ festivals was canceled on Tuesday, after 180 authors boycotted the event and its director resigned, saying she could not be party to silencing a Palestinian author and that moves to ban protests and slogans after the Bondi Beach mass shooting threatened free speech. Louise Adler, the Jewish daughter of Holocaust survivors, said Tuesday she was quitting her role at the Adelaide Writers’ Week in February, following a decision by the festival’s board to disinvite a Palestinian-Australian author. The novelist and academic Randa Abdel-Fattah said the move to bar her was “a blatant and...