dashboards release v4.29.1

Add a nav bar between the four Envoy Gateway dashboards, like the Cilium ones have.

Give Envoy Gateway | Clusters a readable uid. Links to its old random uid stop resolving.
Rename the cluster variable on Cilium Agent logs to cluster_id, matching the other Cilium dashboards so the selection carries across links.
Rename workload_cluster to cluster_id on the Envoy Gateway dashboards, so the selection carries when moving between them. On Clusters its label is K8s Cluster, to tell it apart from the Envoy cluster selector.
Hide the datasource selector on the Cilium and Envoy Gateway dashboards and point it at the default datasource, instead of the exported uids that only resolved in the Grafana a board came from.

Drop the Cluster selector from Envoy Gateway | Clusters. Every panel also matched on the namespace, resource and rule selectors, which compose the same Envoy cluster name.

Give Cilium | Agent its own uid instead of reusing the retired Cilium metrics dashboard’s, which kept it from being created.
Give Envoy Gateway | Control Plane its own uid instead of reusing the retired Global dashboard’s, which kept it from being created.