Support K8s clusters with custom cluster domains for Pixie cloud

[ddelnano]

Kubernetes provides the ability to configure the domain for a cluster (via the --cluster-domain kubelet argument. This changes the default cluster.local zone to a custom domain. There is work to support custom cluster domains on the Vizier side (#1581 (comment)), but the cloud should also work with custom cluster domains.

[ddelnano]

If a cloud is deployed to a cluster with a custom domain, the cloud proxy server ends up in a crash loop with the following error.

2024/09/03 16:12:40 [emerg] 8#8: host not found in resolver "kube-dns.kube-system.svc.cluster.local" in /usr/local/openresty/nginx/conf/nginx.conf:43
nginx: [emerg] host not found in resolver "kube-dns.kube-system.svc.cluster.local" in /usr/local/openresty/nginx/conf/nginx.conf:43