perf[Sidebar]: refine el-scrollbar__bar css

src/styles/sidebar.scss

@@ -22,6 +22,9 @@
     .horizontal-collapse-transition {
       transition: 0s width ease-in-out, 0s padding-left ease-in-out, 0s padding-right ease-in-out;
     }
+    .el-scrollbar__bar.is-vertical{
+      right: 0px;
+    }
     .scrollbar-wrapper {
       height: calc(100% + 15px);
       .el-scrollbar__view {