controllers: unload failed avis from dossier

This avoid the subsequent dossier update to fail because some Avis
may be invalid.

app/controllers/concerns/create_avis_concern.rb

@@ -34,6 +34,7 @@ module CreateAvisConcern
         end
       end
     )
+    dossier.avis.reload # unload non-persisted avis from dossier
 
     persisted, failed = create_results.partition(&:persisted?)