fix(ci): fail benchmarks if build failed

Otherwise the benchmark steps will run indefinitely.

Ideally this job would be skipped instead, but because of the way
things are set up to start in paralell, we can't skip this job midway
through.

lol

.github/workflows/main.yml

@@ -356,10 +356,16 @@ jobs:
         run: godot --editor --headless --quit-after 100 || true
       - name: Wait for build
         uses: fountainhead/action-wait-for-check@v1.2.0
+        id: wait-for-build
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           checkName: "Build (linux, x86_64, release) #${{ github.run_number }}"
           ref: ${{ github.event.pull_request.head.sha || github.sha }}
+      - name: Fail if build failed
+        if: ${{ steps.wait-for-build.outputs.conclusion != 'success' }}
+        run: |
+          echo "Build failed, can't benchmark!"
+          exit 1
       - name: Install binary build artifacts
         uses: actions/download-artifact@v4
         with: