By Davide Barbuscia and Lewis Krauskopf (Reuters) – Signs of stress are growing in the global financial system, sparking worries over everything from contagion between markets to ruptures in financial products. The concerns come as central banks around the world furiously tighten monetary policy in their fight to tame inflation, creating an environment investors and policymakers say is fertile ground for episodes of financial instability. Investors got a taste of the eye-popping volatility such episodes can bring last month, when a blowout in UK debt reverberated around the world. Though the B…