Moving Grafana links to Tamland manifest

Part of gitlab-com/gl-infra/tamland#67 (closed). Downstream changes https://gitlab.com/gitlab-com/gl-infra/tamland/-/merge_requests/515.

This MR adds Grafana dashboard urls to the Tamland manifest. This way Tamland doesn't need to be aware how the url is built.

For example (hiding other fields to focus on the ones being added):

    "ai-assisted": {
         ...
         "overviewDashboard": {
            "name": "ai-assisted Service Overview Dashboard",
            "url": "https://dashboards.gitlab.net/d/ai-assisted-main"
         },
         "resourceDashboard": {
            "kube_container_cpu": {
               "name": "ai-assisted Service | kube_container_cpu resource Dashboard",
               "url": "https://dashboards.gitlab.net/d/alerts-sat_kube_container_cpu/?var-environment=gprd&var-type=ai-assisted&var-stage=main&var-component=kube_container_cpu"
            },
            "kube_container_rss": {
               "name": "ai-assisted Service | kube_container_rss resource Dashboard",
               "url": "https://dashboards.gitlab.net/d/alerts-sat_kube_container_rss/?var-environment=gprd&var-type=ai-assisted&var-stage=main&var-component=kube_container_rss"
            },
            "kube_go_memory": {
               "name": "ai-assisted Service | kube_go_memory resource Dashboard",
               "url": "https://dashboards.gitlab.net/d/alerts-sat_kube_go_memory/?var-environment=gprd&var-type=ai-assisted&var-stage=main&var-component=kube_go_memory"
            },
            "kube_horizontalpodautoscaler_desired_replicas": {
               "name": "ai-assisted Service | kube_horizontalpodautoscaler_desired_replicas resource Dashboard",
               "url": "https://dashboards.gitlab.net/d/alerts-sat_kube_horizontalpodautoscaler/?var-environment=gprd&var-type=ai-assisted&var-stage=main&var-component=kube_horizontalpodautoscaler_desired_replicas"
            },
            "kube_pool_cpu": {
               "name": "ai-assisted Service | kube_pool_cpu resource Dashboard",
               "url": "https://dashboards.gitlab.net/d/alerts-sat_kube_pool_cpu/?var-environment=gprd&var-type=ai-assisted&var-stage=main&var-component=kube_pool_cpu"
            },
            "kube_pool_max_nodes": {
               "name": "ai-assisted Service | kube_pool_max_nodes resource Dashboard",
               "url": "https://dashboards.gitlab.net/d/alerts-sat_kube_pool_max_nodes/?var-environment=gprd&var-type=ai-assisted&var-stage=main&var-component=kube_pool_max_nodes"
            },
            "open_fds": {
               "name": "ai-assisted Service | open_fds resource Dashboard",
               "url": "https://dashboards.gitlab.net/d/alerts-sat_open_fds/?var-environment=gprd&var-type=ai-assisted&var-stage=main&var-component=open_fds"
            },
            "ruby_thread_contention": {
               "name": "ai-assisted Service | ruby_thread_contention resource Dashboard",
               "url": "https://dashboards.gitlab.net/d/alerts-sat_ruby_thread_contention/?var-environment=gprd&var-type=ai-assisted&var-stage=main&var-component=ruby_thread_contention"
            }
         }
      },