sched/tune: Increase the cgroup limit to 8

We have 7 groups that is: background/ camera-daemon/ foreground/ rt/
nnapi-hal/ top-app and root group. Adding another one for testing.

Bug: 150582812
Test: Build
Change-Id: I2d749a7bde4ad4c7c05f7218c9a5f39f8533acae
Signed-off-by: Wei Wang <wvw@google.com>
(cherry picked from commit 33b0444720e2d492326e4713179d5363472aba8b)
Signed-off-by: davidchao <davidchao@google.com>