ipv6: adjust tests after setting IPv6 route metric for manual addresses
Since commit 03e1cc96a5dc3d9a9b86f60810a330332c484a94, NetworkManager also sets the correct route-metric for device-routes for manual IPv6 addresses. Previously, it would only use the correct metric for IPv4 device-routes and IPv6 device-routes for IPv6 addresses obtained from SLAAC/autoconf.
Adjust the tests.
not yet tested