ipv6: fix @ipv6_add_static_address_manually_not_active to not expect …

…IPv6 link local address

Before https://github.com/NetworkManager/NetworkManager/pull/75 (1.11.1 and older), NetworkManager would also create link local addresses for externally assumed devices. The previous version of the test correctly tested that behavior. But I think this is not desired behavior.

Note, that commonly NetworkManager keeps disconnected devices IFF_UP, with "addrgenmode none". That is a terrible hack, to get carrier change events for the device without IPv6 (link local) addresses.

When the user starts externally configuring addresses on the interface, NetworkManager noticies this and generates an externally assumed connection. In this mode, NetworkManager must no longer interfere with whatever the user is doing.

This also means, to not re-add the IPv6 link local address, although that might be quite unexpected to the user. It is also a change in behavior with 1.11.2.

@Build:master