Rebecca Grossman was legally impaired the night she ran over and killed two boys in Westlake Village in 2020, a Los Angeles County District Attorney’s Office detective who is an expert in making such determinations told a civil court jury Monday. Testifying in Van Nuys Superior Court, Detective Michael Takacs said the “totality of the circumstances,” including Grossman’s field sobriety test and an examination of events involving her that took pl…