I made changes to /var/lib/jenkins/jenkins.model.JenkinsLocationConfiguration.xml and then clicked on "Reload Configuration from Disk" in the Jenkins UI, and the Jenkins Location section on the Configure page still showed the original values. I had to do a service jenkins restart in order for the changes to be picked up.

I'm trying to spin up my jenkins server using Chef, hence why I am trying to modify this xml file rather than simply updating the values through the Web UI. There didn't seem to be a REST API endpoint for what I'm trying to do either.