The line between fact and cliche has always been rather tenuous when it comes to movies about famous musicians, considering that so many have tread the same self-destructive path. While their event-filled, often tragic stories entice filmmakers, they also complicate the task of transcending material that can seem old hat or veer into parody. Steve Chagollan reports. Thanks in large part to the successes of “Ray” and “Walk the Line,” that cinematic tightrope will be attempted many times in the coming months. On Friday “La Vie en Rose,”with Marion Cotillard as the hard-drinking Parisian chanteuse Edith Piaf, opens in New York and Los Angeles. Steve Chagollan reports.