Chaos has hit the beach in one of San Diego’s most exclusive coastal neighborhoods as teens are taking part in informal “fight clubs” — and police say social media is fueling the surge.In recent week, La Jolla, a wealthy seaside community known for its upscale homes and scenic coastline, has seen a spike in what authorities describe as fight club-style disturbances at Marine Street Beach, a popular local surf spot.“These meetups are not random,” SDPD Sgt.