Simplify test workflow to match E2E pattern exactly

- Use same command as E2E workflow: --grafana-dir instead of --grafana-ref/--build-id/--version
- Remove GitHub token setup since E2E workflow doesn't use it
- This tests if core dagger build works with same approach as E2E

.github/workflows/test-dagger-build.yml

@@ -15,14 +15,15 @@ jobs:
           path: ./grafana
           persist-credentials: false
 
-      - name: Test release build command (single architecture)
+      - name: Test core build (same as E2E workflow)
         uses: dagger/dagger-for-github@e47aba410ef9bb9ed81a4d2a97df31061e5e842e
         with:
           version: "0.9.3"
           verb: run
-          args: --silent go -C grafana run ./pkg/build/cmd artifacts -a targz:grafana:linux/amd64 --grafana-ref=${{ github.sha }} --build-id=${{ github.run_number }} --version=11.4.8-test
+          args: go -C grafana run ./pkg/build/cmd artifacts -a targz:grafana:linux/amd64 --grafana-dir="${PWD}/grafana" > out.txt
 
+      - run: mv "$(cat out.txt)" grafana.tar.gz
       - name: Check if artifacts were created
         run: |
-          ls -la dist/
-          echo "Release build completed successfully!"
+          ls -la grafana.tar.gz
+          echo "Core build completed successfully!"