manifest: update sdk-zephyr#19502

nordic-segl wants to merge 1 commit intonrfconnect:mainnrfconnect/sdk-nrf:mainfrom

nordic-segl:NRFX-6832_Enable-system_off-tests-on-nrf54l20pdknordic-segl/sdk-nrf:NRFX-6832_Enable-system_off-tests-on-nrf54l20pdkCopy head branch name to clipboard