Reduce diff with EE in Groups::UpdateService

Signed-off-by: Rémy Coutable <remy@rymai.me>

app/services/groups/update_service.rb

@@ -11,6 +11,8 @@ module Groups
 
       return false unless valid_share_with_group_lock_change?
 
+      before_assignment_hook(group, params)
+
       group.assign_attributes(params)
 
       begin
@@ -28,6 +30,10 @@ module Groups
 
     private
 
+    def before_assignment_hook(group, params)
+      # overriden in EE
+    end
+
     def after_update
       if group.previous_changes.include?(:visibility_level) && group.private?
         # don't enqueue immediately to prevent todos removal in case of a mistake