core: log a recognizable message when a unit succeeds, too
    
    We already are doing it on failure, let's do it on success, too.
    
    Fixes: #10265
    (cherry picked from commit 523ee2d41471bfb738f52d59de9b469301842644)
    
    Related: #1737283
    
    patch_name: 0380-core-log-a-recognizable-message-when-a-unit-succeeds.patch
    present_in_specfile: true
    location_in_specfile: 380
    squash_commits: true