Use native arm64 runner for RTK validation

.github/workflows/pr2841-diagnostic.yml

@@ -8,7 +8,7 @@ on:
 
 jobs:
   diagnose:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04-arm
     steps:
       - name: Checkout
         uses: actions/checkout@v7
@@ -19,9 +19,6 @@ jobs:
         with:
           path: ./claude_desktop/
 
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v4
-
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v4