use right translationAuthorPrefix in authorContributionFormat

private_includes/base/default_songinfo_style.ily

@@ -54,7 +54,7 @@
         (poetAndComposerEqualPrefix "")
         (poetPrefix "")
         (composerPrefix "")
-        (translationPrefix "")
+        (translationAuthorPrefix "")
         (pronunciationPrefix "")
         (compositionPrefix "")
         (adaptionTextPrefix "")
@@ -177,4 +177,4 @@
                   )))))
       (make-null-markup)
     )
-}
+}