boards: arm: qemu_cortex_m0: filter out a couple of failing tests

We filter out the following kernel tests
- tickless_concept
- timer_api
from the set of tests running on QEMU Cortex-M0 platform,
as the tests consistently fail on QEMU. In addition, we
add a workaround for kernel/interrupt test, so it can
successfully execute on QEMU Cortex-M0.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>