Kiali openid setup and gke oauth secrets
What
- Configure Kiali OpenID authentication as per https://kiali.io/docs/configuration/authentication/openid/#using-with-google-cloud-platform--gke-oauth2
- Define secrets for Oauth client_id and client_secret as well as the kiali signing key.
Why
Related Issue: https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/24158