By Sinead Cruise, Matt Scuffham and Megan Davies LONDON/NEW YORK (Reuters) – Global banks including Citigroup Inc, JPMorgan Chase & Co and Societe Generale face pressure to commit to remaining as custodian banks in Russia, as rivals and funds fret they may lose services critical to future investment in the country. Traders, bankers and executives from three other financial institutions told Reuters they were seeking or had sought reassurances on behalf of clients on each bank’s long-term plans for these businesses, which clear, settle and safeguard billions of dollars of Russian holdings. Cust…