[meta] Improve Infrastructure Code-Base

[matze]

This ticket serves as context for our long-term adventure of improving the infrastructure code-base. Tickets directly blocking this one are considered refactoring issues, though these may help to implement projects upcoming in the near future. Especially prioritization should be aligned with such tasks, in order to save testing effort.

Overview

Ticket	Status	Resolution	Summary	Component	Owner
#3065	closed	fixed	Allow for host-specific Puppet guest OS configuration	Infrastructure	matze
#3574	closed	fixed	Refactor Puppet class base into class adblockplus	Infrastructure	matze
#3575	reviewing		Improve Puppet module logrotate	Infrastructure	matze
#3587	closed	fixed	Refactor Puppet class users into type adblockplus::user	Infrastructure	matze
#3638	closed	fixed	Refactor hiera('servers') into Puppet class adblockplus::host	Infrastructure	matze
#3669	closed	fixed	Refactor Puppet class adblockplus::log::uplink	Infrastructure	matze
#3686	closed	fixed	Replace Exec['fetch_sitescripts'] with Class['sitescripts']	Infrastructure	matze
#3789	closed	fixed	Explicitly set $group parameter in resource definitions	Infrastructure	ferris
#3818	closed	fixed	Remove custom Puppet stages	Infrastructure	matze
#4728	closed	fixed	Remove hard-coded references from statsmaster sitescripts.ini template	Infrastructure	matze