b78ed11b81
We're no longer providing Xenial test nodes with the switch to Nodepool in Zuul. Remove configuration for Xenial mirroring. I believe that we'll need to follow this up with manual cleanups to actually remove the content with reprepro as dropping the config doesn't lead to deleting files. This will only prevent time spent attempting to update the files. Change-Id: Ib07804d510d978fed3760dd97f9725bc9520e266