Drop Kubelet labelmap relabel for node_name

* Originally, Kubelet and CAdvisor metrics used a labelmap
relabel to add Kubernetes SD node labels onto timeseries
* With https://github.com/poseidon/typhoon/pull/596 that
relabel was dropped since node labels aren't usually that
valuable. `__meta_kubernetes_node_name` was retained but
the field name is empty
* Favor just using Prometheus server-side `instance` in
queries that require some node identifier for aggregation
or debugging

Fix https://github.com/poseidon/typhoon/issues/823

addons/prometheus/config.yaml

@@ -34,7 +34,7 @@ data:
     - job_name: 'kubernetes-apiservers'
       kubernetes_sd_configs:
       - role: endpoints
-      
+
       scheme: https
       tls_config:
         ca_file: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
@@ -74,7 +74,7 @@ data:
     - job_name: 'kubelet'
       kubernetes_sd_configs:
       - role: node
-      
+
       scheme: https
       tls_config:
         ca_file: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
@@ -82,10 +82,6 @@ data:
         insecure_skip_verify: true
       bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
 
-      relabel_configs:
-      - action: labelmap
-        regex: __meta_kubernetes_node_name
-
     # Scrape config for Kubelet cAdvisor. Explore metrics from a node by
     # scraping kubelet (127.0.0.1:10250/metrics/cadvisor).
     - job_name: 'kubernetes-cadvisor'
@@ -100,9 +96,6 @@ data:
         ca_file: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
       bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
 
-      relabel_configs:
-      - action: labelmap
-        regex: __meta_kubernetes_node_name
       metric_relabel_configs:
       - source_labels: [__name__, image]
         action: drop
@@ -121,13 +114,11 @@ data:
       - source_labels: [__meta_kubernetes_node_label_node_kubernetes_io_controller]
         action: keep
         regex: 'true'
-      - action: labelmap
-        regex: __meta_kubernetes_node_name
       - source_labels: [__meta_kubernetes_node_address_InternalIP]
         action: replace
         target_label: __address__
         replacement: '${1}:2381'
-    
+
     # Scrape config for service endpoints.
     #
     # The relabeling allows the actual service scrape endpoint to be configured
@@ -172,7 +163,7 @@ data:
       - source_labels: [__meta_kubernetes_service_name]
         action: replace
         target_label: job
-      
+
       metric_relabel_configs:
       - source_labels: [__name__]
         action: drop