Applies the pre-merge CI failure control to the tasks (#3457)

Applied the pre-merge CI failure control to the tasks stage, as it is
done in the general test stage
Co-authored-by: Kelly Guo <kellyg@nvidia.com>

.github/workflows/build.yml

@@ -76,6 +76,20 @@ jobs:
         retention-days: 1
         compression-level: 9
 
+    - name: Check Test Results for Fork PRs
+      if: github.event.pull_request.head.repo.full_name != github.repository
+      run: |
+        if [ -f "reports/isaaclab-tasks-report.xml" ]; then
+          # Check if the test results contain any failures
+          if grep -q 'failures="[1-9]' reports/isaaclab-tasks-report.xml || grep -q 'errors="[1-9]' reports/isaaclab-tasks-report.xml; then
+            echo "Tests failed for PR from fork. The test report is in the logs. Failing the job."
+            exit 1
+          fi
+        else
+          echo "No test results file found. This might indicate test execution failed."
+          exit 1
+        fi
+
   test-general:
     runs-on: [self-hosted, gpu]
     timeout-minutes: 180