This effectively reverts commit cd89026c5f ('core: add dependent
multicast route configured by kernel for IPv6').
It's not clear to me why this was done or why it would be correct.
True, kernel automatically adds multicast route like
multicast ff00::/8 dev $IFACE table local proto kernel metric 256 pref medium
But NetworkManager ignores all multicast routes for now. So the dependent
routes cannot contain multicast routes as they are not handled. Also,
the code added a unicast route, so I don't understand why the comment
is talking about multicast.
This seems just wrong. Drop it.
(cherry picked from commit c29d995000)
40bc834176