tests: userspace: Do not assign promptless THREAD_USERSPACE_LOCAL_DATA
tests: userspace: Do not assign promptless THREAD_USERSPACE_LOCAL_DATA

Assignments have no effect on promptless symbols. Flagged by
https://github.com/zephyrproject-rtos/zephyr/pull/20742.

This symbol should already be getting enabled if CONFIG_USERSPACE is
enabled, because CONFIG_ERRNO is default y and has

    select THREAD_USERSPACE_LOCAL_DATA if USERSPACE

Signed-off-by: Ulf Magnusson <01743f1c1deb1fe75271d62edb65757d98ac0bcb@nordicsemi.no>

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