[nrf noup] boards: Update non-secure target for nrf54l15#2453

nordicjm merged 1 commit intonrfconnect:mainnrfconnect/sdk-zephyr:mainfrom

gchwier:grch_nrf54l15_default_sysbuildgchwier/sdk-zephyr:grch_nrf54l15_default_sysbuildCopy head branch name to clipboard