samples: sht3xd: kconfig: Do not assign promptless SHT3XD_TRIGGER
samples: sht3xd: kconfig: Do not assign promptless SHT3XD_TRIGGER

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

SHT3XD_TRIGGER is already being selected by
SHT3XD_TRIGGER_GLOBAL_THREAD, which is enabled in the same configuration
file.

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

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