Using multi-queue scheduler doesn't work for cmsis_rtos_v2 as it
supports a max of only 32 priority levels which is less than the
total priority levels required by cmsis_rtos_v2 (which is 56).
Hence explicitly asking the tests to use the scalable scheduler.
Signed-off-by: Rajavardhan Gundi <rajavardhan.gundi@intel.com>