Add SPARK_USER

Author: dongjoon-hyun

.github/workflows/build_and_test.yml

@@ -88,6 +88,8 @@ jobs:
             test-group: state-transition
           - mode: static
             test-group: watched-namespaces
+    env:
+      SPARK_USER: spark
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4