LONDON — Nigel Farage is having to make do with being a runner-up. Almost a year after his Reform UK won the Runcorn and Helsby by-election on a night of local election euphoria, his party came second in Thursday’s Gorton and Denton contest . But despite not making it all the way in the Greater Manchester parliamentary seat, the populist insurgents are still talking up their chances of becoming the key right-wing challengers in the U.K. And they have a fresh set of numbers to back up their