By Paul Sandle and Dawn Chmielewski LONDON/LOS ANGELES (Reuters) – BT said it would merge its sports TV unit with Discovery’s Eurosport in Britain and Ireland, enabling it to retain Premier League soccer for its customers while sharing the burden of expensive broadcast rights. BT, a former British telecoms monopoly, moved into sport in 2013 when it beat Rupert Murdoch’s Sky to Champions League rights, hoping that exclusive content would help it stem broadband customer losses. Some investors, however, have fretted about the volatile cost of sports rights, particularly when BT is spending billio…