This change removes RelatedArticles from beta features.
It repurposes the BlacklistSkins config to be a whitelist that describes
when related pages should be shown in the footer.
To avoid enabling related pages on desktop, this depends on a config
change that makes use of the new configuration option.
Simplify browser tests to reflect the new status quo.
Bug: T146436
Bug: T160076
Depends-On: I522e0182d1c3d9261bd0561c3ec0c789b6431c7a
Change-Id: I84da1fb33a901a6365375d00d192af35422ff0b0
Introduce a new config variable `RelatedArticlesFooterBlacklistedSkins`
to control skins that are allowed to show ReadMore in the footer.
As before Minerva beta mode is always allowed to show.
Depends-on: I366c8656a0f14a7069053b2e6199caac20471ea4
Depends-on: Ie4ac3c11e81eeea9f5b4a7161a64477cb5d60f07
Bug: T144047
Change-Id: I1663ab25083d9d907f288e60d506831bebb67945
This old classic returns again.
A browser test fails when this is not enabled as it asserts that
the user is in beta.
Bug: T120715
Change-Id: I2c5339ba959318a3b995a28e22f3df375ae53103
