Update nothing-here-block to utilize Pajamas spacing scale

Changelog: changed

app/assets/stylesheets/framework/blocks.scss

@@ -6,7 +6,7 @@
 
 .nothing-here-block {
   text-align: center;
-  padding: 20px;
+  padding: 16px;
   color: $gl-text-color;
   font-weight: $gl-font-weight-normal;
   font-size: 14px;