Former rivals and current Senate hopefuls on Tuesday extolled former President Donald J. Trump’s record and denounced, sometimes inaccurately, the levels of illegal immigration and crime in the country. On the second night of the Republican National Convention, former primary challengers to Mr. Trump, including Nikki R. Haley, who served as United Nations ambassador in his administration, Gov. Ron DeSantis of Florida and Senator Ted Cruz of Texas made their case for Mr. Trump to return to...