Neon Carnival hit a major milestone this weekend ... and yeah, they still know how to throw a party! The iconic Coachella after-hours bash celebrated its 15th anniversary in the desert, bringing out a stacked crowd and turning the invite-only event into its usual late-night celeb playground. Ty Dolla $ign , Tyga , YG , Chris Brown and Mario were all in the mix, with Ryan Garcia right there too ... the group even shared a prime booth near the stage as the night rolled on. Mario had a standout