sched: Disable default sched_autogroup to avoid the DBA performance regression

sched: Disable default sched_autogroup to avoid the DBA performance regression

SCHED_AUTOGROUP optimizes the scheduler for common desktop workloads by
automatically creating and populating task groups. Though it helps desktop CPU
hungry workloads(linke build jobs), we found that it crteates 10% regerssion
on DBA perfromance.

Swingbench benchmark run for OLTP shows below:

@ UEK4-with-schedauto		3.18.4-5	7073
@ UEK4-without-schedauto	3.18.4-5	7873

So to have best of both words, we make the SCHED_AUTOGROUP feature
available on UEK kernels but the default state is disabled.

One can enable it using the sysctrl (kernel.sched_autogroup_enabled)

Orabug: 20476603

Tested-by: Thomas Tanaka <thomas.tanaka@oracle.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>