SAN FRANCISCO — Chinese hackers have stepped up their probes against the U.S. tech sector since Russia’s invasion of Ukraine, an FBI official said on Thursday. “We’ve actually seen — here in the San Francisco area — an uptick in reconnaissance from Chinese” threat actors, Elvis Chan, an assistant special agent in charge at the bureau’s San Francisco field office, said during a panel discussion at the RSA conference. Chan, who manages the field office’s cyber branch, said Chinese hacking groups have increased their scans, in part, because they “want to see” how the U.S. and its private sector react…