Update the chef-client version on a node as a test run
As a first exploratory experiment in our effort to upgrade to chef 15.x, in substitution of https://gitlab.com/gitlab-com/gl-infra/infrastructure/issues/7248, I propose we take one of our chef provisioned nodes and try out the upgrade. A viable candidate seems to be a node on pre, perhaps a web node, since it has no production, release or ops dependencies. This would serve as a data point to estimate the work ahead of us.