By James Davey LONDON (Reuters) - After a decade pushing its non-food business, Tesco , Britain's biggest retailer is changing, and a conspicuous focus on fresh produce greets shoppers at its newly styled superstores. "Customers were saying they felt we didn't have the right products in our shop," said Kiran Sudan, store manager at the recently refurbished Kensington superstore in west London, whose catchment area is a multi-cultural mishmash of affluent dwellings and social housing. ...