test: fix TestIPv6FlowHopsIPv6, ensure topology is ready
test: fix TestIPv6FlowHopsIPv6, ensure topology is ready

Change-Id: I27690f50c825d6259afa50aaf217840ee3370cf1
Reviewed-on: https://softwarefactory-project.io/r/7508
Reviewed-by: Sylvain Afchain <b9baee1c2e4cc202620c6529e0c0bd3dbc38b6dc@gmail.com>
Tested-by: Sylvain Afchain <b9baee1c2e4cc202620c6529e0c0bd3dbc38b6dc@gmail.com>
Workflow: Sylvain Afchain <b9baee1c2e4cc202620c6529e0c0bd3dbc38b6dc@gmail.com>

safchain/skydive,safchain/skydive,skydive-project/skydive,skydive-project/skydive,lebauce/skydive,skydive-project/skydive,skydive-project/skydive,skydive-project/skydive,lebauce/skydive,skydive-project/skydive,safchain/skydive,safchain/skydive,safchain/skydive,lebauce/skydive,safchain/skydive,lebauce/skydive,safchain/skydive,lebauce/skydive,lebauce/skydive,safchain/skydive,skydive-project/skydive,lebauce/skydive,lebauce/skydive