fix(接口测试): 修复断言xpath不生效的缺陷

--bug=1037509 --user=王孝刚 【接口测试】接口定义-断言-响应体断言-XPath-XML-设置了未生效
https://www.tapd.cn/55049933/s/1480887
--bug=1037497 --user=王孝刚
【接口测试】接口定义-断言-响应体断言-XPath-HTML-设置了未生效
https://www.tapd.cn/55049933/s/1480890

backend/services/project-management/src/main/java/io/metersphere/project/api/assertion/body/MsXPathAssertionItem.java

@@ -21,6 +21,6 @@ public class MsXPathAssertionItem extends MsBodyAssertionItem {
     private String expectedValue;
 
     public boolean isValid() {
-        return StringUtils.isNotBlank(expression) && StringUtils.isNotBlank(expectedValue);
+        return StringUtils.isNotBlank(expression);
     }
 }

frontend/src/components/business/ms-assertion/comp/ResponseBodyTab.vue

@@ -93,7 +93,12 @@
     <!-- xPath开始 -->
     <div v-if="activeTab === ResponseBodyAssertionType.XPATH" class="mt-[16px]">
       <div class="text-[var(--color-text-1)]">{{ t('ms.assertion.responseContentType') }}</div>
-      <a-radio-group v-model="activeResponseFormat" class="mb-[16px] mt-[16px]" type="button" size="small">
+      <a-radio-group
+        v-model="condition.xpathAssertion.responseFormat"
+        class="mb-[16px] mt-[16px]"
+        type="button"
+        size="small"
+      >
         <a-radio key="XML" value="XML">XML</a-radio>
         <a-radio key="HTML" value="HTML">HTML</a-radio>
       </a-radio-group>