By Fanny Potkin, Eduardo Baptista and Tony Munroe SINGAPORE/BEIJING (Reuters) – Even as China bars 1.4 billion citizens from Twitter, its local authorities are splurging on global advertising on the site, helping make the country the platform’s fastest-growing overseas ad market and one of its largest non-U.S. revenue sources. A Reuters review of publicly available government tenders, budget documents and promoted tweets from 2020 to 2022 shows local authorities and Chinese Communist Party propaganda offices for cities, provinces and even districts across the country have flocked to Twitter to…