By Ron Bousso LONDON (Reuters) -Shell is set to conclude nearly a century of operations in Nigerian onshore oil and gas after agreeing to sell its subsidiary there to a consortium of five mostly local companies for up to $2.4 billion. The British energy giant pioneered Nigeria’s oil and gas business beginning in the 1930s. It has struggled for years with hundreds of onshore oil spills as a result of theft, sabotage and operational issues that led to costly repairs and high-profile lawsuits. Since 2021, Shell has sought to sell its Nigerian oil and gas business, but will remain active in Nigeri…