Replace stats/follows with v2/stats/subscribers in People screen

[staskus]

The current v1.1/sites/{site_id}/follows endpoint we use doesn't work for non-admins, but the new v2/sites/{site_id}/subscribers one does work. So until we update it, editors who go to Stats Subscribers in the app and tap View More won't be able to load the full Subscriber list (aka. the People view)

[dangermattic]

Thanks for reporting! 👍

[staskus]

Putting out of scope, due to findings on pdDOJh-2RW-p2:

The problem is that, due to how the data is organized in different databases, we deliver the features in different ways depending on the number of subscribers of your site. Let’s see what those differences are:
We can aggregate data for small sites, and we call this endpoint to return the subscriber list: /wpcom/v2/sites/[blog-id]/subscribers. We cannot aggregate data for big sites, so we need to pass a subscriber type all the time, using this endpoint instead: /wpcom/v2/sites/[blog-id]/subscribers_by_user_type.