By Steve Scherer and David Ljunggren OTTAWA (Reuters) – Police began towing trucks from central Ottawa on Friday and stepped up arrests of protesters in a bid to end a trucker-led movement that has blockaded Canada’s capital for three weeks and embarrassed Prime Minister Justin Trudeau’s government. The protesters have lined heavy trucks outside parliament and Trudeau’s office, and Ottawa police, fearing escalation or violence, had sought to disperse them with fines and threats. But with dozens of trucks still occupying downtown, police on Thursday arrested two of the movement’s leaders and ch…