refactor: replace Dockerfile.e2e with ConfigMap volume mount for E2E plugin loading

Delete custom Docker image approach per board directive. Plugin is now
loaded into stock Headlamp via a ConfigMap volume mount:

- Delete Dockerfile.e2e
- deploy-e2e-headlamp.sh creates a ConfigMap from dist/ and mounts it
  into the stock ghcr.io/headlamp-k8s/headlamp image
- Helm values use extraVolumes/extraVolumeMounts for the ConfigMap
- No custom images, no PVCs, no kubectl exec/cp

Co-Authored-By: Paperclip <noreply@paperclip.ing>

deployment/e2e-ci-runner-rbac.yaml

@@ -6,7 +6,7 @@
 # namespace to deploy and tear down a dedicated Headlamp instance via Helm.
 #
 # No kube-system access needed — E2E tests use a separate namespace.
-# No PVC management — plugin is baked into the Docker image.
+# Plugin is loaded via ConfigMap volume mount — no custom Docker images.
 #
 # Prerequisites:
 #   kubectl create namespace headlamp-e2e

deployment/headlamp-e2e-values.yaml

@@ -1,19 +1,17 @@
 ---
 # Headlamp Helm values for E2E testing.
 #
-# Uses a custom Docker image (built from Dockerfile.e2e) with the plugin
-# pre-installed. No PVCs, no volume mounts, no deployment patching.
-#
-# The E2E workflow builds the image, pushes to ghcr.io, and deploys this
-# Helm release in the headlamp-e2e namespace.
+# Uses the stock Headlamp image with the plugin loaded via a ConfigMap
+# volume mount. No custom Docker images — the plugin dist/ is packaged
+# as a ConfigMap by deploy-e2e-headlamp.sh.
 #
 # Usage:
 #   helm install headlamp-e2e headlamp/headlamp \
 #     -n headlamp-e2e --create-namespace \
 #     -f deployment/headlamp-e2e-values.yaml \
 #     --set image.registry=ghcr.io \
-#     --set image.repository=privilegedescalation/headlamp-polaris-e2e \
-#     --set image.tag=<sha>
+#     --set image.repository=headlamp-k8s/headlamp \
+#     --set image.tag=latest
 
 config:
   pluginsDir: /headlamp/plugins
@@ -21,3 +19,13 @@ config:
 
 service:
   type: ClusterIP
+
+extraVolumes:
+  - name: polaris-plugin
+    configMap:
+      name: headlamp-polaris-plugin
+
+extraVolumeMounts:
+  - name: polaris-plugin
+    mountPath: /headlamp/plugins/headlamp-polaris
+    readOnly: true