fix(接口测试): 修复场景变量隔离问题

--bug=1012107 --user=赵勇 【接口测试】github#12512，场景变量引用不对 https://www.tapd.cn/55049933/s/1138047

backend/src/main/java/io/metersphere/api/dto/definition/request/MsScenario.java

@@ -149,9 +149,10 @@ public class MsScenario extends MsTestElement {
         if (arguments != null && (this.variableEnable == null || this.variableEnable)) {
             Arguments valueSupposeMock = ParameterConfig.valueSupposeMock(arguments);
             // 这里加入自定义变量解决ForEach循环控制器取值问题，循环控制器无法从vars中取值
-            scenarioTree.add(valueSupposeMock);
             if (this.variableEnable != null && this.variableEnable) {
                 scenarioTree.add(ElementUtil.argumentsToUserParameters(valueSupposeMock));
+            } else {
+                scenarioTree.add(valueSupposeMock);
             }
         }
         if (this.variableEnable == null || this.variableEnable) {