Merge branch 'crameleon/discourse-postfix' into 'production'
    
    [MR was originally "Include Postfix with Discourse"]
    
    Remove Postfix state references in Discourse profile
    
    This allows profile.discourse to be applied independently.
    The original version of this commit included `profile.postfix`
    instead, but as per the discussion in
    !1392 (comment 9343) it should not be required to reload the service on map updates.
    
    See merge request infra/salt!1392