[nrf fromlist] boards: nordic: nrf54l20pdk: Remove obsolete board#3068

nordic-segl wants to merge 3 commits intonrfconnect:mainnrfconnect/sdk-zephyr:mainfrom

nordic-segl:Remove-obsolete-nrf54l20pdk-boardnordic-segl/sdk-zephyr:Remove-obsolete-nrf54l20pdk-boardCopy head branch name to clipboard