[BUGFIX] Added row_id to the flat action indexer so the value isn't set to 0 for new products when using index on save

Author: lewisvoncken

app/code/Magento/Catalog/Model/Indexer/Product/Flat/Action/Indexer.php

@@ -175,6 +175,7 @@ public function write($storeId, $productId, $valueFieldSuffix = '')
 
         if (!empty($updateData)) {
             $updateData += ['entity_id' => $productId];
+            $updateData += ['row_id' => $productId];
             $updateFields = [];
             foreach ($updateData as $key => $value) {
                 $updateFields[$key] = $key;