With the code as it stands, it would no longer be necessary to copy the FILTERED_LIST (nothing modifies it anymore).

I spent a little time stepping through the code, and my objection is perhaps enough of an edge case that we wouldn't care (although some folks are worried about course authors screwing up the tabs if we expose this setting). But here is the issue:

If you specify "notes" or "combinedopenended" in advanced_modules, a tab will be added for the LMS. In the case of "notes", it is a tab named "My Notes", and for "combinedopenended", it is "Open Ended Panel".

To do this, the code you touched in course.py modifies the "tabs" property. However, with this PR, "tabs" would also be visible in the Advanced Settings. This leads to 2 slightly confusing things.

1) Modifying advanced_modules may update "tabs". But we don't make that clear.

2) If you modify both advanced_modules and tabs, your change to tabs will be ignored.