updates: test Silverblue install on UEFI as well as BIOS
    
    https://bugzilla.redhat.com/show_bug.cgi?id=2268505 made it
    clear that this is a bit of a hole. We don't test installing the
    Silverblue image we build on UEFI, only on BIOS. Add this as a
    separate test so we don't uselessly upload a disk image we won't
    use for any follow-on tests.
    
    This also adds an anaconda build that fixes a bug in this path
    as a workaround for F40, so the test won't fail on all F40
    updates.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>