fix(carousel): [carousel] modify carousel style (#2376)

Author: James-9696

packages/theme/src/carousel/index.less

@@ -227,7 +227,7 @@
       width: 16px;
       height: auto;
       transform: translateY(50%);
-      padding: 2px 4px;
+      padding: 2px 0;
       margin: 0;
 
       .@{carousel-prefix-cls}__indicator {