When joining a cluster, replicate config files instead of creating them
When we're joining a cluster (ie. on the second and every next manager node), in the installation procedure, we create all the config files, then remove them, and replicate them (via syncthing).
Instead of creating-then-deleting, we can simply not create them.
This will allow the installation/join to be faster.
If this is an easy win (low effort, low risk) please add to sprint 8. If not, we should defer to 5.2.