…without making the topic subscriptions feature available in user preferences.
Follow-up to these commits, which added these checks in ad-hoc ways:
* 9420f22e9d
* f3422f40a6
* 23a490deca
* a555db7892
Bug: T284491
Change-Id: If2e3fb1e06d1cc489fbca14796ed77c83bb52991
We don't display [subscribe] buttons on your user talk page,
but the API still allows those subscriptions.
Use the same approach as for mentions to ensure this doesn't cause
duplicate notifications.
Remove some code in SubscribedNewCommentPresentationModel,
now guaranteed to be unused.
Change-Id: I99a276a48d8562552ed2c54cc0323e8e428845fd
