PB-500 give preference to main style over container style.

Author: paras89

app/code/Magento/PageBuilder/view/adminhtml/web/template/content-type/column-group/default/master.html

@@ -7,7 +7,7 @@
 
 <div class="pagebuilder-column-group"
      attr="data.main.attributes"
-     ko-style="Object.assign(data.main.style, data.container.style)"
+     ko-style="Object.assign(data.container.style, data.main.style)"
      css="data.main.css">
     <render args="masterTemplate"></render>
 </div>