sched: tune: be more conservative about boosting top app

Currently with top-app boost value being fixed to 1 we get a tonn of
random small tasks hanging on the big cluster that have frankly no business
staying there. Let's be smarter about top-app group and only allow
apps that are actually on the display (w/ adj == 0) to stay on big cores.

minari: Remove code sched boost/prefer idle overrides

Signed-off-by: Yaroslav Furman <yaro330@gmail.com>
Change-Id: Ib3c634f4e929ce8ccfb52f317bfa4185391af38c
Signed-off-by: minaripenguin <minaripenguin@users.noreply.github.com>