Merge branch '34909-pipeline-dropdown-z-index' into 'master'

Increase z index of mini pipeline dropdown

Closes #34909

See merge request !12767

app/assets/stylesheets/pages/merge_requests.scss

@@ -125,7 +125,7 @@
 
     .dropdown-menu {
       margin-top: 11px;
-      z-index: 200;
+      z-index: 300;
     }
 
     .ci-action-icon-wrapper {