Upload: crop the success icon when list type is "picture" (#9285)

packages/theme-chalk/src/upload.scss

@@ -384,6 +384,7 @@
   @include m(picture) {
     .el-upload-list__item {
       overflow: hidden;
+      z-index: 0;
       background-color: #fff;
       border: 1px solid #c0ccda;
       border-radius: 6px;