MC-13925: Hard Coded Margins On individual Button

- Updated advanced data entity reference for button item margin default

Author: Hwashiang Yu

app/code/Magento/PageBuilder/Test/Mftf/ActionGroup/ContentTypeButtonActionGroup.xml

@@ -175,7 +175,7 @@
         <comment userInput="Validate default margin" stepKey="comment"/>
         <executeJS function="return window.getComputedStyle({{buttonItemPage.jsButtonSelector(buttonIndex)}}).margin" stepKey="getDefaultMarginValueStage"/>
         <assertEquals stepKey="checkDefaultMarginValueStage">
-            <expectedResult type="string">{{PageBuilderMarginPropertyButtonItemDefault.value}}</expectedResult>
+            <expectedResult type="string">{{PageBuilderMarginsPropertyButtonItemDefault.value}}</expectedResult>
             <actualResult type="variable">getDefaultMarginValueStage</actualResult>
         </assertEquals>
     </actionGroup>