Restored original event, added deprecated message to the event so that it is backward compatible.

Author: dverkade

app/code/Magento/CatalogSearch/Model/Indexer/Fulltext/Action/DataProvider.php

@@ -204,6 +204,12 @@ public function getSearchableAttributes($backendType = null)
             /** @var \Magento\Eav\Model\Entity\Attribute[] $attributes */
             $attributes = $productAttributes->getItems();
 
+            /** @deprecated */
+            $this->eventManager->dispatch(
+                'catelogsearch_searchable_attributes_load_after',
+                ['engine' => $this->engine, 'attributes' => $attributes]
+            );
+            
             $this->eventManager->dispatch(
                 'catalogsearch_searchable_attributes_load_after',
                 ['engine' => $this->engine, 'attributes' => $attributes]