revert: use default Grafana images from Docker Hub (#3)

Remove custom Harbor image configuration to use default Grafana
images (grafana/grafana) from Docker Hub. This resolves the
image pull issues and uses the official Grafana images.

Author: surrealwolf

loki/base/grafana-helmchart.yaml

@@ -47,7 +47,4 @@ spec:
             isDefault: true
             jsonData:
               maxLines: 1000
-    # Image configuration
-    image:
-      repository: harbor.dataknife.net/dockerhub/grafana/grafana
-      tag: "11.0.0"  # Latest stable version
+    # Image configuration - using default Grafana images from Docker Hub

loki/overlays/nprd-apps/grafana-helmchart.yaml

@@ -59,7 +59,4 @@ spec:
               httpHeaderName1: "X-Scope-OrgID"
             secureJsonData:
               httpHeaderValue1: "fake"
-    # Image configuration
-    image:
-      repository: harbor.dataknife.net/dockerhub/grafana/grafana
-      tag: "11.0.0"  # Latest stable version
+    # Image configuration - using default Grafana images from Docker Hub