sysbuild: Remove IRON variant#23088

tomchy merged 1 commit intonrfconnect:mainnrfconnect/sdk-nrf:mainfrom

tomchy:bugfix/nrf54h/NCSDK-NONE_Remove_iron_boardtomchy/sdk-nrf:bugfix/nrf54h/NCSDK-NONE_Remove_iron_boardCopy head branch name to clipboard