fix(性能测试): 修复导出报告图错乱的问题

--bug=1019484 --user=刘瑞斌 【性能测试】github#17585，性能测试未设置监控信息，导出性能报告为pdf，部分数据丢失，有表格重叠<有监控机器时pdf正常> https://www.tapd.cn/55049933/s/1298350

Closes #17585

frontend/src/common/js/utils.js

@@ -278,7 +278,7 @@ export function exportPdf(name, canvasList) {
       let blankHeight = a4Height - currentHeight;
 
       if (leftHeight > blankHeight) {
-        if (blankHeight < 200) {
+        if (blankHeight < 300) {
           pdf.addPage();
           currentHeight = 0;
         }
@@ -292,10 +292,10 @@ export function exportPdf(name, canvasList) {
           leftHeight -= occupation;
           position -= occupation;
           //避免添加空白页
-          // if (leftHeight > 0) {
-          // pdf.addPage();
-          // currentHeight = 0;
-          // }
+          if (leftHeight > 0) {
+            pdf.addPage();
+            currentHeight = 0;
+          }
         }
       } else {
         pdf.addImage(pageData, 'JPEG', 0, currentHeight, imgWidth, imgHeight);