By Julia Payne LONDON (Reuters) – Exxon Mobil is injecting new cash into oil trading in Europe after a retreat on its ambitious expansion plans last year, three people with knowledge of the matter said. Exxon slashed funding for its trading division in 2020 as part of wider cuts, leaving traders without the capital they needed to take full advantage of the volatile oil market during peak COVID-19 lockdowns. The company’s cautious strategy during the pandemic sparked the exodus of some senior-level recruits from the previous couple of years, along with Exxon veterans, after they were restricted…