Fix duplicated Favorites collection

While a user is supposed to have only one Favorites collections, it appears that many of them can be created. We clearly see since it we added collections to the right menu panel in the new web ui.

Also, sometimes when you reload the ui, the Favorites content may change, it is because there is many Favorites for the current user and the fetched one changes randomly.

There must be something wrong or mis-synchronized platform side.