:art: Use the properties system instead of the service root
General comment: we'll need to handle migration of the existing variables to the new properties system.
Would that be fitting to do in the install file? Or isn't that used during updates?
Maybe update - can you check what trigger we use in the plugin:update calls? - though we might need to do both - I think plugin:install is more or less plugin:update...
They can be different, plugn calls the install hooks for install and update for update, but with update just being a link to install in this plugin, they really are the same.