tests: kernel: threads: no-multithreading: Extend test

Extended test to validate following functionality:
- k_busy_wait
- k_timer
- irq_lock/irq_unlock
- k_cpu_idle
- SYS_INIT()

Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
3 files changed