contint: tidy Nodepool slaves config history
Nodepool spawns Jenkins slaves as non ephemeral slaves, that causes the
Jenkins config history plugin to save the configuration each time a node
is spwaned under /var/lib/jenkins/config-history/nodes. Once 32k entries
have been created, the file system refuses to add any more sub
directories and no more instances can be spawned (T127131).
Use Puppet tidy type to garbage collect the Nodepool slaves config
history after just one day. It is quiet unlikely we will ever spawn 32k
builds per day.