Resolve "Merge request refactor displays changes dropdown incorrectly"

app/assets/javascripts/diffs/components/changed_files_dropdown.vue

@@ -66,6 +66,7 @@ export default {
           @click="clearSearch"
         ></i>
       </div>
+      <div class="dropdown-content">
         <ul>
           <li
             v-for="diffFile in filteredDiffFiles"
@@ -120,5 +121,6 @@ export default {
           </li>
         </ul>
       </div>
+    </div>
   </span>
 </template>

app/assets/stylesheets/pages/diff.scss

@@ -737,6 +737,10 @@
   max-width: 560px;
   width: 100%;
   z-index: 150;
+  min-height: $dropdown-min-height;
+  max-height: $dropdown-max-height;
+  overflow-y: auto;
+  margin-bottom: 0;
 
   @include media-breakpoint-up(sm) {
     left: $gl-padding;