seco-mx6.conf: add pre-shutdown scripts for SANTVEND
These scripts are ported from Jethro BSP.
Dear all, On Thursday, 4th September 2025, we will test the new disaster recovery environment. A disaster recovery test will take place between 4:00 PM and 6:00 PM CEST. Please refrain from making any changes, as they will be lost. Once testing is complete, the production environment will be restored. Thank you for your understanding.
These scripts are ported from Jethro BSP.