feat: add labeled version of node_pressure_cpu_waiting_seconds_total

feat: add labeled version of node_pressure_cpu_waiting_seconds_total

This adds the node_pressure_cpu_waiting_seconds_total:labeled variant by joining the metrics to kube_node_labels:labeled.

Discussed in gitlab-com/gl-infra/observability/team#4205 (comment 2547428456)

feat: add the cloud_google_com_gke_nodepool label to k8s node metrics

This takes the label_cloud_google_com_gke_nodepool label from kube_node_labels and propagates through kube_node_labels:labeled to all of the :labeled metrics we generate from it.

This will help us see the the resource utilization of the nodes through the saturation points and more easily correlate it to a specific nodepool.

Part of gitlab-com/gl-infra/observability/team#4205 (comment 2547428456)