refactor(接口测试): 优化正则匹配模块规则 #26797

Signed-off-by: fit2-zhao <yong.zhao@fit2cloud.com>

api-test/backend/src/main/java/io/metersphere/api/dto/definition/request/extract/MsExtract.java

@@ -96,7 +96,8 @@ public class MsExtract extends MsTestElement {
         if (extractRegex.isMultipleMatching()) {
             extractor.setMatchNumber(-1);
         }
-        extractor.setTemplate("$1$");
+        // $1$提取 JSON 响应中的第一个匹配项 $0$用于提取整个 JSON 响应
+        extractor.setTemplate("$0$");
         extract.add(extractor.getRefName());
 
         return extractor;