tests: dynamic_thread: disable on x86
tests: dynamic_thread: disable on x86

This doesn't work properly on x86 unless the dynamic thread
struct allocated gets lucky and is aligned to 16 bytes.
Disabling for now until #17893 is fixed.

Signed-off-by: Andrew Boie <aab045b28152628be6af0e556050d0381fd0a34d@intel.com>

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