fix(e2e): use pnpm-capable workflow branch (PRI-634)

* fix(ci): guard dual-approval job against null pull_request context

When triggered by pull_request_review events, github.event.pull_request
is undefined, which can cause issues when the job tries to access
github.event.pull_request.number. Add a job-level if guard to prevent
the job from running in these conditions.

This addresses the dual approval failures seen on feature branches where
the workflow was running without a valid PR context.

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

* fix(e2e): use pnpm-capable workflow branch

Reference @hugh/add-pnpm-support-plugin-e2e which has pnpm support via corepack.

PRI-634

* fix(e2e): use pnpm-capable workflow branch

Reference @hugh/add-pnpm-support-plugin-e2e which has pnpm support via corepack.

PRI-634

* Update e2e.yaml to use @main and pass plugin-name

Use @main workflow ref and add plugin-name input so the
reusable workflow can derive ConfigMap name and mount path.

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

---------

Co-authored-by: Chris Farhood <chris@farhood.org>
Co-authored-by: Paperclip <noreply@paperclip.ing>

.github/workflows/dual-approval.yaml

@@ -14,6 +14,7 @@ on:
 
 jobs:
   dual-approval:
+    if: github.event.pull_request != null
     uses: privilegedescalation/.github/.github/workflows/dual-approval-check.yaml@main
     secrets: inherit
     with:

.github/workflows/e2e.yaml

@@ -21,3 +21,4 @@ jobs:
       node-version: '22'
       headlamp-version: v0.40.1
       e2e-namespace: headlamp-dev
+      plugin-name: headlamp-kube-vip