[certification] return ipv6 in testharness-discovery script (#1185)
[certification] return ipv6 in testharness-discovery script (#1185)

Current implementation returns on Windows platforms by default IPv4
address and with this commit we will start to return IPv6 link local.
openthread/ot-br-posix,openthread/ot-br-posix,openthread/borderrouter,openthread/ot-br-posix,openthread/borderrouter,openthread/borderrouter,openthread/ot-br-posix,openthread/borderrouter,openthread/ot-br-posix,openthread/borderrouter,openthread/ot-br-posix,openthread/borderrouter