fix(测试跟踪): 没有上传插件时，缺陷列表无法展示

--bug=1020959 --user=陈建星 【测试跟踪】删除jira插件后缺陷管理页面无法打开 https://www.tapd.cn/55049933/s/1317715

test-track/backend/src/main/java/io/metersphere/service/PlatformPluginService.java

@@ -77,7 +77,7 @@ public class PlatformPluginService {
         }
         PluginMetaInfo pluginMetaInfo = pluginManager.getPluginMetaInfoByKey(platform);
         if (PlatformPluginService.isPluginPlatform(platform) && pluginMetaInfo == null) {
-            MSException.throwException(Translator.get("platform_plugin_not_exit") + PlatformPluginService.PLUGIN_DOWNLOAD_URL);
+            return false;
         }
         return pluginMetaInfo == null ? false : pluginMetaInfo.isThirdPartTemplateSupport();
     }