REFACTOR(longhorn): migrate to local-path

- alertmanager, grafana, loki, prometheus: storageClass -> local-path-retain
- Change storage backend configuration

alertmanager/helm-values.yaml

@@ -6,7 +6,7 @@ fullnameOverride: alertmanager
 persistence:
   enabled: true
   size: 1Gi
-  storageClass: longhorn  # Migrated from local-path to Longhorn (replica=3)
+  storageClass: local-path-retain
 
 resources:
   requests:

grafana/helm-values.yaml

@@ -13,7 +13,7 @@ admin:
 persistence:
   enabled: true
   size: 2Gi
-  storageClass: longhorn  # Migrated to Longhorn for HA (replica=2)
+  storageClass: local-path-retain
 
 initChownData:
   enabled: false

loki/helm-values.yaml

@@ -40,7 +40,7 @@ singleBinary:
   persistence:
     enabled: true
     size: 5Gi  # Reduced from 10Gi to save storage
-    storageClass: longhorn  # Migrated from local-path to Longhorn (replica=2)
+    storageClass: local-path-retain
   resources:
     requests:
       cpu: 15m  # Reduced from 50m based on actual usage (10m)

prometheus/helm-values.yaml

@@ -46,7 +46,7 @@ prometheus:
     storageSpec:
       volumeClaimTemplate:
         spec:
-          storageClassName: longhorn
+          storageClassName: local-path-retain
           accessModes: ["ReadWriteOnce"]
           resources:
             requests: