Drop Foreign Key on cataloginventory_stock_item table 

MSI should Drop FK

```
CONSTRAINT `CATINV_STOCK_ITEM_PRD_ID_CAT_PRD_ENTT_ENTT_ID` FOREIGN KEY (`product_id`) REFERENCES `catalog_product_entity` (`entity_id`) ON DELETE CASCADE,
```

on 
```
    <table name="cataloginventory_stock_item" resource="default" engine="innodb" comment="Cataloginventory Stock Item">
```