Revert "Merge pull request #4026 from guardian/fronts-respect-grouping-news"

This reverts commit 49e7c96d023eae59a86adc619adf79114ae75130, reversing
changes made to cdbe5d36eb9f7f1c5079f44896ab517b3f630a2a.
Merge pull request #4049 from guardian/revert-fronts-respect-grouping-news

Revert pull request #4026 — Fronts: new importance settings