By James Davey LONDON (Reuters) – Facing the toughest economic conditions in decades, Britain’s supermarkets are cutting product ranges, searching for cost savings and patrolling each other’s stores to check prices and products as they try to stay one step ahead. Like retailers across the world, UK grocers including market leader Tesco and No. 2 Sainsbury’s are struggling with the soaring cost of supplies, a shortage of key products and workers, and cash-strapped consumers. But they enter the downturn on the back of an already lengthy period of cost cutting due to fierce competition, forcing t…