[grafana] - adds cloudflared tunnel to the grafana deployment.
What
- Adds cloudflare tunnel credentials secret from vault.
- Adds cloudflared deployment.
Why
This enables us to provide a secure connect to cloudflare for Grafana and remove the need for a google load balancer with a public address.
Relates to: https://gitlab.com/gitlab-com/gl-infra/scalability/-/issues/3573