fix(接口测试): 修复场景引用导入接口用例报错java.lang.IndexOutOfBoundsException的缺陷

--bug=1010655 --user=王孝刚
【接口测试】github#11022，场景引用导入接口用例报错java.lang.IndexOutOfBoundsException
https://www.tapd.cn/55049933/s/1110550

backend/src/main/java/io/metersphere/service/RelationshipEdgeService.java

@@ -43,12 +43,13 @@ public class RelationshipEdgeService {
         example.createCriteria()
                 .andSourceIdEqualTo(sourceId)
                 .andTargetIdEqualTo(targetId);
-
+        List<RelationshipEdge> list = relationshipEdgeMapper.selectByExample(example);
+        if (CollectionUtils.isNotEmpty(list)) {
             String graphId = relationshipEdgeMapper.selectByExample(example).get(0).getGraphId();
             updateGraphId(graphId, sourceId, targetId);
-
             relationshipEdgeMapper.deleteByExample(example);
         }
+    }
 
     public void delete(String sourceId ,List<String> targetIds) {
         targetIds.forEach(targetId -> {