[Improve][SeaTunnel-Web] Change JobStatus to enum type to avoid hard coding

Author: wuchunfu

seatunnel-web-it/src/test/java/org/apache/seatunnel/app/utils/JobTestingUtils.java

@@ -99,9 +99,9 @@ private static boolean isFinished(JobPipelineDetailMetricsRes metrics) {
             return false;
         }
         switch (metrics.getStatus()) {
-            case "FINISHED":
-            case "CANCELED":
-            case "FAILED":
+            case FINISHED:
+            case CANCELED:
+            case FAILED:
                 return true;
             default:
                 return false;