Make pipeline action dropdowns consistent

app/assets/stylesheets/framework/dropdowns.scss

@@ -750,6 +750,7 @@
       a,
       button {
         border-radius: 0;
+        box-shadow: none;
         padding: 8px 16px;
         // make sure the text color is not overriden

app/assets/stylesheets/pages/pipelines.scss

@@ -257,6 +257,8 @@
 // Pipeline visualization
 .pipeline-actions {
+  @include new-style-dropdown;
+
   border-bottom: none;
 }