Swap stats is not shown as part of the metrics/resource endpoint

[iholder101]

What happened:

The following:

> kubectl get --raw "/api/v1/nodes/k8s-dev-worker/proxy/metrics/resource"
# HELP container_cpu_usage_seconds_total [STABLE] Cumulative cpu time consumed by the container in core-seconds
# TYPE container_cpu_usage_seconds_total counter
container_cpu_usage_seconds_total{container="kindnet-cni",namespace="kube-system",pod="kindnet-ndczz"} 1.121325 1735032838055
container_cpu_usage_seconds_total{container="kube-proxy",namespace="kube-system",pod="kube-proxy-l5jhs"} 1.100665 1735032838936
container_cpu_usage_seconds_total{container="metrics-server",namespace="kube-system",pod="metrics-server-8598789fdb-nw6cq"} 7.333964 1735032837430
# HELP container_memory_working_set_bytes [STABLE] Current working set of the container in bytes
# TYPE container_memory_working_set_bytes gauge
container_memory_working_set_bytes{container="kindnet-cni",namespace="kube-system",pod="kindnet-ndczz"} 3.2923648e+07 1735032838055
container_memory_working_set_bytes{container="kube-proxy",namespace="kube-system",pod="kube-proxy-l5jhs"} 4.0628224e+07 1735032838936
container_memory_working_set_bytes{container="metrics-server",namespace="kube-system",pod="metrics-server-8598789fdb-nw6cq"} 4.7026176e+07 1735032837430
# HELP container_start_time_seconds [STABLE] Start time of the container since unix epoch in seconds
# TYPE container_start_time_seconds gauge
container_start_time_seconds{container="kindnet-cni",namespace="kube-system",pod="kindnet-ndczz"} 1.7350309825441425e+09
container_start_time_seconds{container="kube-proxy",namespace="kube-system",pod="kube-proxy-l5jhs"} 1.7350309819809804e+09
container_start_time_seconds{container="metrics-server",namespace="kube-system",pod="metrics-server-8598789fdb-nw6cq"} 1.7350309993126562e+09
# HELP node_cpu_usage_seconds_total [STABLE] Cumulative cpu time consumed by the node in core-seconds
# TYPE node_cpu_usage_seconds_total counter
node_cpu_usage_seconds_total 71.41304 1735032832343
# HELP node_memory_working_set_bytes [STABLE] Current working set of the node in bytes
# TYPE node_memory_working_set_bytes gauge
node_memory_working_set_bytes 2.134016e+08 1735032832343
# HELP pod_cpu_usage_seconds_total [STABLE] Cumulative cpu time consumed by the pod in core-seconds
# TYPE pod_cpu_usage_seconds_total counter
pod_cpu_usage_seconds_total{namespace="kube-system",pod="kindnet-ndczz"} 1.145182 1735032830497
pod_cpu_usage_seconds_total{namespace="kube-system",pod="kube-proxy-l5jhs"} 1.108676 1735032837395
pod_cpu_usage_seconds_total{namespace="kube-system",pod="metrics-server-8598789fdb-nw6cq"} 7.336168 1735032831254
# HELP pod_memory_working_set_bytes [STABLE] Current working set of the pod in bytes
# TYPE pod_memory_working_set_bytes gauge
pod_memory_working_set_bytes{namespace="kube-system",pod="kindnet-ndczz"} 3.3222656e+07 1735032830497
pod_memory_working_set_bytes{namespace="kube-system",pod="kube-proxy-l5jhs"} 4.0914944e+07 1735032837395
pod_memory_working_set_bytes{namespace="kube-system",pod="metrics-server-8598789fdb-nw6cq"} 4.732928e+07 1735032831254
# HELP resource_scrape_error [STABLE] 1 if there was an error while getting container metrics, 0 otherwise
# TYPE resource_scrape_error gauge
resource_scrape_error 0

As can be seen, swap stats is not shown here:

> kubectl get --raw "/api/v1/nodes/k8s-dev-worker/proxy/metrics/resource" | grep -i swap
> 

What you expected to happen:
Swap to be included in metrics/resource endpoint stats.

How to reproduce it (as minimally and precisely as possible):

1. Bring up a cluster
2. Install metrics server
3. Run kubectl get --raw "/api/v1/nodes/<NODE-NAME>/proxy/metrics/resource" | grep -i swap

Anything else we need to know?:
Swap stats were introduced in this PR: kubernetes/kubernetes#118865.
It also shows the expected output.

Environment:

• kind version: (use kind version): > kind v0.22.0 go1.21.7 linux/amd64
• Runtime info: (use docker info, podman info or nerdctl info): docker 27.2.1
• OS (e.g. from /etc/os-release): Fedora 39
• Kubernetes version: (use kubectl version): 1.32 (main)
• Any proxies or other special environment settings?: no