By Shreyashi Sanyal and Bansari Mayur Kamdar (Reuters) -European shares were subdued at the close on Monday after choppy trading, as the surge in energy stocks was offset by tinvestor concerns around fighting in Ukraine. The pan-European STOXX 600 was flat after posting its biggest weekly percentage gain since November 2020 on Friday. Investors were closely tracking the war in Ukraine, with European Union governments mulling an oil embargo on Russia as they gather this week with U.S. President Joe Biden for a series of summits aimed at hardening their stance against Moscow. The news sparked a …