feat: click on a blank area of ​​the canvas to hide the form drawer #918 (#1384)

### What problem does this PR solve?
feat: click on a blank area of ​​the canvas to hide the form drawer #918

### Type of change


- [x] New Feature (non-breaking change which adds functionality)

web/src/pages/flow/list/index.less

@@ -56,6 +56,6 @@
 }
 
 .templatesBox {
-  // max-height: 500px;
+  max-height: 70vh;
   overflow: auto;
 }