samples: fix the metairq_dispatch sample sporadically failed on ehl_crb
samples: fix the metairq_dispatch sample sporadically failed on ehl_crb

The metairq sample sometimes failed due to stuck because it has a
potential race when recording the latencies. The previous solution
checks whether the stats.mirq greater than MAX_EVENT. But stats.mirq
might also have a race here. So we change to check the msg sequence,
its correctness ensured by the kernel's message queue.

And also remove the spinlock in previous fix because tests only use
1 CPU, no need to add this. It also improves the fix for #40889,
to prevent test failed sporadically on acrn_ehl_crb and ehl_crb.

Fix #42874.

Signed-off-by: Enjia Mai <7a2de2448a1c31432e87f79c5f6556ebbe33f656@intel.com>

galak/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr