subsys/ztest: Revert "Make 1cpu tests run on CPU 0 specifically"
subsys/ztest: Revert "Make 1cpu tests run on CPU 0 specifically"

This change introduced some weird failures on x86 that will take some
time to untangle, and wasn't a particularly important feature to
merge.  Revert for now.

This reverts commit adc901aa6a39caffd7971ff99456b26414cd3793.

Signed-off-by: Andy Ross <c70f9a6bf6ee0cd69c8af4ce5e6b131945769315@intel.com>

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