NYPD cops had a front-row seat to a five-on-one brawl — but let the violence play out rather than doing their jobs to break it up, The Post has learned.A 14-year-old girl was slapped, punched, kicked and even shocked with a stun gun by a group of five other girls after a basketball game around 7 p.m. Sunday on East 125th Street near Madison Avenue in Harlem.Police reports initially listed the girl as 11.During the roughly 4-minute beatdown, cops sat idly in nearby cruisers — but they didn’t get out until the girl was bloody and bruised, a Post photographer observed.At least 20 police cars...…NYPD cops had a front-row seat to a five-on-one brawl — but let the violence play out rather than doing their jobs to break it up, The Post has learned.A 14-year-old girl was slapped, punched, kicked and even shocked with a stun gun by a group of five other girls after a basketball game around 7 p.m. Sunday on East 125th Street near Madison Avenue in Harlem.Police reports initially listed the girl as 11.During the roughly 4-minute beatdown, cops sat idly in nearby cruisers — but they didn’t get out until the girl was bloody and bruised, a Post photographer observed.At least 20 police cars...WW…