fix(e2e): add E2E workflow and deploy scripts for headlamp-kube-vip-plugin

Adds:
- .github/workflows/e2e.yaml (calls plugin-e2e.yaml reusable workflow)
- scripts/deploy-e2e-headlamp.sh (deploys Headlamp with kube-vip plugin ConfigMap)
- scripts/teardown-e2e-headlamp.sh (cleans up E2E resources)

Fixes PRI-729: E2E DNS failure caused by missing E2E workflow in this repo.

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

.github/workflows/e2e.yaml

@@ -0,0 +1,23 @@
+name: E2E Tests
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: e2e-${{ github.repository }}
+  cancel-in-progress: false
+
+jobs:
+  e2e:
+    uses: privilegedescalation/.github/.github/workflows/plugin-e2e.yaml@hugh/add-pnpm-support-plugin-e2e
+    with:
+      node-version: "22"
+      headlamp-version: v0.40.1
+      e2e-namespace: headlamp-dev