In an ornate Brussels concert hall, Bashar Murad, a Palestinian songwriter, stood before hundreds and delivered a mournful performance of Nina Simone’s “I Wish I Knew How It Would Feel to Be Free” in English and Arabic. When the final notes faded, the audience erupted. The performance Tuesday evening was part of a broader protest movement against this week’s Eurovision Song Contest in Vienna, with Israel’s participation sparking anger over its devastating military campaign in Gaza and elsewhere. Five nations, including Spain and Ireland, are boycotting the kitschy extravaganza as performers from 35 countries compete in Europe’s annual pop music competition, which marks its 70th anniversary this year.…