By Oliver Hirt (Reuters) -Credit Suisse Group AG is expected to announce Ulrich Koerner as its new chief executive officer, replacing Thomas Gottstein in a bid to shore up confidence in the bank, two sources familiar with the situation said on Tuesday. Pressure has been mounting on Gottstein for months over major scandals and losses racked up during his two-year tenure that have hammered shares and angered investors. When Gottstein took the helm in 2020, he promised a “clean slate” for the bank, which was recovering from an internal spying scandal that cost his predecessor Tidjane Thiam his jo…