We now only have afs-slug.sh in jenkins/scripts/ and it is only
used by nodepool/scripts/configure_mirror.sh. Move the file into the
nodepool/scripts directory and adjust paths.
Remove copying of jenkins/scripts from nodepool, the directory does not
exist anymore.
Remove 89-jenkins-scripts, we don't need it anymore.
Depends-On: https://review.openstack.org/548393
Change-Id: I13cac791d70a2e5bcb0de1ba0adcd79e1b0aee9f
91400af8ba