Remove static IPv6 support from network role — all hosts use SLAAC
(method=auto). Simplifies NM templates, argument_specs, and resolved.conf.
gateway sysctl accept_ra=2 is now unconditional when gateway_enabled.

Co-authored-by: Claude.ai

The pihole lookup DNS queries when the VPN connection is up was slow.
One of the culprits was the quad9 servers were taking long time when
using VPN
The other issue was the previous routing tables that used to work with
the fritzbox (with DHCP) which wasn't fully working was conflicting with
the VPN route tables and causing loops and delays.

Now most of the VPN queries are working fast but some requests are
taking some time, probably due to the VPN trying to check/block ads and
malware!

Also minor fixing to the pre tasks and documentation

The testing was failing because the use of the example files with the
same domain names, resulted in the files and the molecule variable were
being merged and therefore running tasks that would fail on test
(example, setting a fake VPN connection that wouldn't start).