Freeze break request for mutter

[Florian Müllner <fmuellner gnome org>]

Hey everyone!

As you may know, the tiling improvements in 3.26 involved a grouping
behavior that turned out rather unpopular, and after some discussion
we decided that the feature needed more work to be actually useful and
reverted the change on the stable branch:

https://gitlab.gnome.org/GNOME/mutter/commit/415584344a5d4b5

Our idea was to refine the grouping behavior this cycle, but in the
end it didn't happen. So I would like to apply that revert to the
upcoming 3.28.0 release as well.

I'm sorry this slipped into the hard code freeze period, I should have
remembered this before :-(

-- Florian