Creating the tf user has shifted the uid/gid of centos and all further users

[mboisson]

The tf user that gets created since #316 is created with uid:1000, which means centos shifts from uid:1000/gid:1000 to uid:1001/gid:1001.
This means that a previous local user with uid:1001, which uses PR ComputeCanada/puppet-magic_castle#312 can no longer be created, because it fails with

Jan 20 20:58:38 mgmt1.int.archimedes-dev.c3.ca puppet-agent[1640]: GID 1001 already exists, use allowdupe to force group creation
Jan 20 20:58:38 mgmt1.int.archimedes-dev.c3.ca puppet-agent[1640]: (/Stage[main]/Profile::Users::Local/Profile::Users::Local_user[nixuser]/Group[nixuser]/ensure) change from 'absent' to 'present' failed: GID 1001 already exists, use allowdupe to force group creation

Since, in our case, that UID has a massive number of files on the filesystem, it really needs to keep the same UID as before, and especially, centos should not use the uid/gid 1001, since it's typically not a privileged uid/gid.