By Sheila Dang (Reuters) -Elon Musk filed a motion on Friday opposing Twitter Inc’s request to fast-track a trial over his plan to terminate his $44 billion deal for the social media firm. Musk’s lawyers, in papers filed with the Delaware Chancery Court, said Twitter’s “unjustifiable request” to rush the merger case to trial in two months should be rejected. It is the latest move in what promises to be a major legal showdown between Twitter and Musk. The San Francisco-based company is seeking to resolve months of uncertainty for its business as Musk tries to walk away from the deal for what he…