container: Use GOARCH to create the manifest list.
    
    We need to make sure to use the GOARCH architecture spec
    to create the manifest list. The spec differs from koji
    architecture for armhfp --> arm and x86_64 --> amd64.
    
    Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1997789
    
    Signed-off-by: Clement Verna <cverna@tutanota.com>