Revert "Update index.less (#3173)"

This reverts commit 534cbe391b4f66b711f7c314a3c38a5535555029.

src/components/GlobalHeader/index.less

@@ -4,7 +4,7 @@
 
 .header {
   height: @layout-header-height;
-  padding: 0 8px 0 0;
+  padding: 0;
   background: #fff;
   box-shadow: 0 1px 4px rgba(0, 21, 41, 0.08);
   position: relative;