Update _main-sidebar.scss (#3082)

fixed scrollbar show in sidebar

build/scss/_main-sidebar.scss

@@ -19,7 +19,7 @@
 
 .sidebar {
   height: calc(100% - (#{$main-header-height-inner} + #{$main-header-bottom-border-width}));
-  overflow-y: auto;
+  overflow-y: initial;
   padding-bottom: $sidebar-padding-y;
   padding-left: $sidebar-padding-x;
   padding-right: $sidebar-padding-x;