Create fqdn for kiali using external-dns

What

The change creates a fully qualified domain name (FQDN) for Kiali using external DNS. This will make it easier to access Kiali from outside the cluster.

Kiali FQDN will be componse of the cluster name, environment followed by the gke.gitlab.net subdomain.

Diff:

► VirtualService/istio-system/kiali drifted

metadata
  + one map entry added:
    annotations:
    │ external-dns.alpha.kubernetes.io/hostname: kiali.pre-gitlab-gke.pre.gke.gitlab.net
    │ external-dns.alpha.kubernetes.io/ttl: 3600

metadata.generation
  ± value change
    - 2
    + 3

metadata.labels.kustomize.toolkit.fluxcd.io/name
  ± value change
    - flux-components-kiali
    + flux-components-cert-manager-clusterissuer

spec.hosts.0
  ± value change
    - kiali.pre-gitlab-gke.pre.gitlab.net
    + kiali.pre-gitlab-gke.pre.gke.gitlab.net

Why

Related issue: https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/24157