Update service-insight functional tests

[vepatel]

https://github.com/nginx/kubernetes-ingress/blob/main/tests/suite/test_virtual_server_service_insight.py needs updating for cross-namespace

[github-actions]

Hi @vepatel thanks for reporting!

Be sure to check out the docs and the Contributing Guidelines while you wait for a human to take a look at this 🙂

Cheers!