Associate users with groups for usage monitoring

#5764 - Refine #5315 and create subtasks

#5804 - Use annotations instead of labels for usernames on pods

#5806 - Use kube_pod_annotations for usernames instead of kube_pod_labels in Grafana dashboards

#5824 - Make user and group information from JupyterHub available to Prometheus

#5892 - Enable jupyterhub-groups-exporter on test hub

#5825 - Users and user groups can be associated to existing usage metrics through PromQL and visualised in Grafana

#5805 - Phased rollout of manage_groups feature for all GitHub authenticated hub deployments

#5983 - Rollout jupyterhub-groups-exporter for all hubs with manage_groups feature

#6174 - Populate and monitor JupyterHub group memberships

#6176 - Add an alert for jupyterhub-groups-exporter pod dying

#6177 - Set resource requests and limits appropriately for jupyterhub-groups-exporter

#5978 - Write a blog post to wrap up “Associate users with groups for usage monitoring” initiative

#6196 - Hold retro on Platform Initiative #5315: Associate users with groups for usage monitoring