The Troubadour has probably never been mentioned as many times from the stage of the Greek as it was Friday night. This was because the headliner, country star Megan Moroney , had to keep pinching herself — figuratively, not literally — as she surveyed the sold-out crowd on her second night playing the storied amphitheater. The last time she headlined in L.A., she kept remarking, it had been at the 500-capacity Troubadour, and now, two years later, she was filling the 5,900-seat Greek two