Fix border overflow bug on design note

Design note backgrounds overflow border slightly when
note is selected. Specifying border radius solves this.

app/assets/stylesheets/components/design_management/design.scss

@@ -109,6 +109,8 @@
       padding: $gl-padding;
       list-style: none;
       transition: background $gl-transition-duration-medium $general-hover-transition-curve;
+      border-top-left-radius: $border-radius-default; // same border radius used by .bordered-box
+      border-top-right-radius: $border-radius-default;
 
       a {
         color: inherit;

changelogs/unreleased/fix-design-note-border-radius.yml

+---
+title: Fix background overflow when design note is selected
+merge_request: 36931
+author:
+type: fixed