“Drama at the dress rehearsal of Tosca at the Maggio Musicale Fiorentino!  This is an open rehearsal because it is a Telethon benefit performance. Ruggero Raimondi, indisposed, is replaced by Giovanni Meoni. Adina Nitescu, the second cast Tosca, is voiceless. The first cast Tosca, Violeta Urmana, cannot go on stage because she doesn’t want to get…