contint: Apache could not start without IPv6

Whenever we are lacking IPv6 (aka in labs), the `Listen [:1]:80`
statement would prevent Apache from starting up.

The has_ipv6 variable in the template would let us skip the IPv6 listen
statement.  Disable it for labs realm.

Change-Id: I507dbed356fac0b40f749655ac5d2e55618b875b
Merge "contint: Apache could not start without IPv6" into production