fix(gce-ipv6-property): return empty string for IPv6 address in GCE
fix(gce-ipv6-property): return empty string for IPv6 address in GCE

scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests