Foreman PXE loader naming conventions expects SecureBoot option to be loading grub2/shim.efi but recent versions of RHEL introduced shimaa64.efi and also shimia32.efi therefore we should change names to follow this.

Additionally, Foreman lists "Grub UEFI SecureBoot" which was resolving to grub/shim.efi but Grub1 does not support SecureBoot via shim. It can be signed manually if user wants to, but that does not need an extra option, therefore the "Grub UEFI SecureBoot" will be removed completely.

Finally, items grub/bootx64.efi and grub/bootia32.efi should be named grub/grubx64.efi and grub/grubia32.efi respectively to follow naming convention with grub2.

This patch will require foreman ticket #19556 (ship foreman-bootloaders package) to be present, it will respect the new naming conventions.