Merge branch 'backport-empty-panel-heading-styles-from-related-issues' into 'master'

Backport empty panel heading from EE related issues

See merge request !12153

app/assets/stylesheets/framework/panels.scss

@@ -34,6 +34,10 @@
     }
   }
 
+  .panel-empty-heading {
+    border-bottom: 0;
+  }
+
   .panel-body {
     padding: $gl-padding;