A former top State Police official who killed himself left behind a detailed suicide note focusing on Attorney General Andrew Cuomo's probe of the Dirty Tricks Scandal and feared an ongoing investigation of ex-Gov. Eliot Spitzer's involvement with prostitutes, The Post has learned. Recently retired State Police Inspector Gary Berwick, who hung himself in the garage of his home on Thursday, wrote a wide-ranging and sometimes rambling suicide note, sources said. The letter zeroed in on his close relationship with former acting State Police Superintendent Preston Felton, a key figure in last summer's political espionage scandal who was dumped after...