Openstack 16 to 17 FFU - During LEAPP upgrade UEFI systems do not boot due to invalid /boot/grub2/grub.cfg

Issue

• During the Openstack 16 to 17 Fast-forward upgrade, UEFI systems may fail to reboot during the LEAPP OS upgrade if an old or invalid /boot/grub2/grub.cfg is present.

• With tripleo-ansible version 3.3.1-17.1.20240603220822.8debef3 a change was introduced that made the default UEFI grub.cfg (/boot/efi/EFI/redhat/grub.cfg) a stub redirect to the default /boot/grub2/grub.cfg. This is consistent with the default RHEL 9 configuration and generally both grub.cfg files should be the same; however, it is possible that an incompatible grub.cfg exists causing a boot issue.

• One possible scenario is that an incompatible grub.cfg exists from a previous OS upgrade such as RHEL 7 -> 8 where RHEL 7 used non-BLS grub configuration.