zdtm: split sched_prio00 on two parts

sched_prio00 tests only priorities and sched_policy00
tests scheduling policy.

scheduling policy can not be changed in OpenVZ containers.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>