CHICAGO — Mayor Brandon Johnson on Wednesday stood behind his administration’s bumpy attempts to house migrants in large tent encampments before the winter, a week after Gov. J.B. Pritzker blew up plans for the first such camp amid blistering environmental concerns. Addressing reporters after a City Council meeting, the mayor said his approach to vetting the land that would have housed Chicago’s first government-run migrant camp was appropriate, while admitting there’s room for improvement in the future. “I’m very much committed to environmental justice,” Johnson said, adding Pritzker’s admini…