Remove Fedora repository fastmirror selection
    
    Fast mirror selection somehow stopped working. If disabled, the
    difference is around 20 seconds for the 'Prepare build environment' step
    (2:49 versus 3:09), so while we are saving, currently it is not a lot.
    
    Also remove explicit nodejs stream choice, it seems to be not needed
    anymore (again).
    
    Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Armando Neto <abiagion@redhat.com>