Remove non-browser e2e test infrastructure

- Delete .github/workflows/e2e.yaml
- Delete playwright.config.ts
- Delete e2e/ directory (auth.setup.ts, kube-vip.spec.ts)
- Delete scripts/deploy-e2e-headlamp.sh and teardown-e2e-headlamp.sh
- Remove e2e and e2e:headed scripts from package.json
- Remove @playwright/test devDependency

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

.github/workflows/e2e.yaml

@@ -1,24 +0,0 @@
-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@main
-    with:
-      node-version: '22'
-      headlamp-version: v0.40.1
-      e2e-namespace: headlamp-dev
-      plugin-name: headlamp-kube-vip