fix galley webhook integration test (#17026)
fix galley webhook integration test (#17026)

https://github.com/istio/istio/pull/16857 changes how galley manages
the validation webhooks' ownerRef but did not update the integration
test because its not run by default.
geeknoid/istio,geeknoid/istio,smawson/istio,geeknoid/istio,istio/istio,geeknoid/istio,smawson/istio,istio/istio,geeknoid/istio,geeknoid/istio,istio/istio,smawson/istio,smawson/istio,istio/istio,smawson/istio,smawson/istio,istio/istio