rpm/network: disable IPv6 autoconfiguration
rpm/network: disable IPv6 autoconfiguration

When the IPv6 address is given to us from the contextualization
variables, use it and disable autoconfiguration.

(cherry picked from commit 7ffdd1fa306d437a6435853c6fb4e987c55b960b)

puppetmaster/addon-context-linux,fasrc/addon-context-linux,OpenNebula/addon-context-linux,fasrc/addon-context-linux,OpenNebula/addon-context-linux,puppetmaster/addon-context-linux