We should disable the beta mode and its features via a config change to simplify the mobile site going into desktop refresh.
The mobile beta mode currently has 2 features enabled:
1) jump to top (added Sept 2015 Bug: T98701, Change-Id: I11a8ccb1e701644dcb328bfec9fe346f75ae1b71)
2) categories (added January 2015, Bug:T86496) available only to logged in users
The last time features were promoted from beta to stable was an addition of the contributions button to the main menu in August 2016 T141787). On top of this a share feature was added in Oct 2018 but never enabled for users.
We should disable the beta for the time being for the following reasons:
* The addition of the share feature (and it's lack of enabling in production) suggests that the beta is not well understood.
* The fact two features added in 2015 have not been promoted to stable in 4 years yet are subject to bugs is concerning
* It's hard to justify maintaining the code for this feature given its lack of use and in particular the addition of the new AMC mode.
* About 100 people are added to beta a day: https://grafana.wikimedia.org/d/000000566/overview?panelId=2&fullscreen&orgId=1
* We continue to maintain this code and have to take it into account in all bug reports and QA steps.
* It's not clear when opting into Advanced mobile contributions mode what a user is getting.
* It's not clear to developers/QA testers how advanced mobile contributions mode differs from stable.
* We are about to start desktop refresh and potentially freeze the mobile site. Keeping it as simplified as possible going into that project seems sensible.
= acceptance criteria
 Remove back to top (it's useful but doesn't really fit AMC)
 Put the categories feature in AMC mode.
 Disable the beta
= Developer notes
This is a config only change
wgMFEnableBeta = false;
wgMinervaEnableBackToTop['amc'] = true;
wgMinervaShowCategoriesButton['amc'] = true;
= Additional notes
* If we don't want to put the back to top feature in AMC mode, we might want to turn it into a gadget.
* If wanted, we could later simplify the categories feature to work like desktop (a link of plain links)