LONDON—Concerns over slowing China growth and a spike in COVID-19 cases in Europe stymied the global equity markets rally on Friday with stocks struggling to cling to recent record highs and the euro looking on track for a second straight week of losses. While U.S. stocks closed at a record high on Thursday, aided by consumer discretionary and tech sectors, the optimism faded noticeably in the Asian session with the regional index set to close down 1 percent for the week. European stock indices edged higher in early London trading on Friday though sentiment was more cautious with a European stock market volatility gauge holding near two-week highs. “Markets are consolidating after heady gains in the dollar and front-end bond yields in recent weeks and investors will turn their focus to the preliminary PMI data next week,” said Kenneth Broux, an FX strategist at Societe Generale in London. “In the …