By Gleb Garanich and Natalia Zinets BUCHA/LVIV, Ukraine (Reuters) – Moscow signalled on Friday it was scaling back its ambitions in Ukraine to focus on territory claimed by Russian-backed separatists as Ukrainian forces went on the offensive to recapture towns on the outskirts of the capital Kyiv. In the first big sign that Western sanctions on Moscow were impacting investment from China, sources said state-run Sinopec Group, Asia’s biggest oil refiner, halted talks on a petrochemical investment and a venture to market Russian gas. In the month since they launched their invasion of Ukraine, Ru…