LONDON (Reuters) - Britain's Sainsbury's plans to cut hundreds of management jobs as it seeks to bring its main supermarket operation and its Argos general merchandise arm closer together, it said on Tuesday.It said the jobs would go in commercial, retail, finance, digital, technology and human resources functions. It did not give a precise figure.Sainsbury's also said that since the start of its 2019-20 financial year in March, its senior leadership team has been reduced by over 20%.The group..