ACP2E-3064: Error Page Builder when editing CMS Block

- Remove "allow-same-origin" for security reasons.

Author: bubasuma

app/code/Magento/PageBuilder/view/adminhtml/web/template/page-builder.html

@@ -31,6 +31,7 @@
         <with args="stage">
             <render></render>
         </with>
-        <iframe attr="id: 'render_frame_' + id" sandbox="allow-scripts allow-same-origin" style="position: absolute; width:0; height:0; border: none;"></iframe>
+        <!-- Do not modify the "sandbox" attribute without approval from a security engineer -->
+        <iframe attr="id: 'render_frame_' + id" sandbox="allow-scripts" style="position: absolute; width:0; height:0; border: none;"></iframe>
     </if>
 </div>