WASHINGTON — The FBI was justified in opening its investigation into ties between the Trump presidential campaign and Russia and did not act with political bias, despite “serious performance failures” up the bureau’s chain of command, the Justice Department’s internal watchdog said in a highly anticipated report Monday. The findings undercut President Donald Trump’s claim that he was the target of a “witch hunt.” The report from the Justice Department’s inspector general revealed for the first time that the FBI had also sent an informant to record a conversation with a “high-level Trump campaign official,” who was not considered a subject in the Russia probe.