Enable IPv6 in dokken tests

[Firefishy]

No description provided.

[Firefishy]

Annoyingly it seems npm (and node) use IPv6 addresses by default over IPv4 addresses and does not fallback.

• node --network-family-autoselection is available in very recent node versions to enable Happy Eyeballs, but requires bleeding edge fixes to work properly.
• Alternative is to change precedence back to IPv4 eg: node --dns-result-order=ipv4first "$(which npm)"

[tomhughes]

I think the solution is to use a ULA adddress instead of 2001:db8 as ULA addresses are treated as lower priority than IPv4 when resolving names. I've added a commit to test that out...