spec file: do not create /etc/ssh/ssh_config.orig if unchanged
    
    The upgrade removes the line
    HostKeyAlgorithms ssh-rsa,ssh-dss
    if present in /etc/ssh/ssh_config and creates a backup in
    /etc/ssh/ssh_config.orig, even if no change was applied.
    
    Create the backup file only if the file was changed.
    
    Fixes: https://pagure.io/freeipa/issue/9610
    
    Signed-off-by: Florence Blanc-Renaud <flo@redhat.com>
    Reviewed-By: Michal Polovka <mpolovka@redhat.com>