MAGETWO-92218: ExtensionAttributes Installation Failure

- Fallback to always to factory so we don't have signature mismatches

Author: tjwiebell

app/code/Magento/PageBuilder/Plugin/Catalog/Model/Product/Attribute/RepositoryPlugin.php

@@ -55,9 +55,7 @@ public function afterGet(
         \Magento\Catalog\Api\Data\ProductAttributeInterface $result
     ) {
         $isPageBuilderEnabled = $result->getData('is_pagebuilder_enabled');
-        $extensionAttribute = $result->getExtensionAttributes()
-            ? $result->getExtensionAttributes()
-            : $this->extensionAttributesFactory->create();
+        $extensionAttribute = $this->extensionAttributesFactory->create();
         $extensionAttribute->setIsPagebuilderEnabled($isPageBuilderEnabled);
         $result->setExtensionAttributes($extensionAttribute);
         return $result;