kernel: sched: Mitigate non-boosted tasks preempting boosted tasks

Currently when a boosted task is scheduled we use prefer_idle to try and
get it to an idle core. Once it's scheduled, there is a possibility we
can schedule a non-boosted task on the same core where the boosted task
is running on. This change aims to mitigate that possibility by checking
if the core we're targeting has a boosted task and if so, use the next
best idle core instead.

Bug: 131626264
Bug: 144961676
Change-Id: I3d321e1c71f96526f55f7f3a56e32db411311aa2
Signed-off-by: Miguel de Dios <migueldedios@google.com>
Signed-off-by: Jimmy Shiu <jimmyshiu@google.com>
Signed-off-by: minaripenguin <minaripenguin@users.noreply.github.com>