A 16-year-old boy was busted for allegedly hiding a gun in his sock that his pal used to shoot another teen on board a Queens rush-hour train, cops and law enforcement sources said Thursday.  The unidentified 16-year-old was picked up Wednesday afternoon by members of the NYPD’s Neighborhood Safety Team – who recognized him as wanted in connection to the 6 p.m. Monday A train shooting that left a 15-year-old paralyzed from the waist down, according to authorities and sources.  He was charged with attempted murder, assault and criminal possession of a weapon, police said.  The teen was charged with attempted murder in connection to the 6 p.m. Monday A train shooting that left a 15-year-old paralyzed from the waist down, police said. Kevin C.…