This commit updates the DNS query locality parsing so that the virtual
IP for an imported service can be queried.
Note that:
- Support for parsing a peer in other service discovery queries was not
added.
- Querying another datacenter for a virtual IP is not supported. This
was technically allowed in 1.11 but is being rolled back for 1.13
because it is not a use-case we intended to support. Virtual IPs in
different datacenters are going to collide because they are allocated
sequentially.