By Yoruk Bahceli (Reuters) – Euro zone markets, where investors once snapped up scarce bonds at any price, may be at a turning point after demand at government debt sales fell last month versus a year ago. The first such decline in January since 2015, it marks a shift in supply and demand dynamics for bonds as the European Central Bank prepares to scale back its pandemic bond-buying stimulus scheme. For the first time since 2019, net debt supply will outstrip ECB buying, which according to UBS, will lead to the biggest annual net supply increase since 2015 when the central bank launched quanti…