MCP-602: Fix failed MFTF test

- Fix AdminNotAvailableProductQtyInShoppingCartValidationTest

Author: aa-kashk

app/code/Magento/Quote/Model/Quote/Item/AbstractItem.php

@@ -318,17 +318,16 @@ public function getStore()
     }
 
     /**
-     * Checking item data
+     * Set and Validate Item Qty
      *
-     * @return $this
+     * @return void
      */
-    public function checkData()
+    public function setQuantity()
     {
         $this->setHasError(false);
         $this->clearMessage();
 
         $qty = $this->_getData('qty');
-
         try {
             $this->setQty($qty);
         } catch (\Magento\Framework\Exception\LocalizedException $e) {
@@ -338,7 +337,16 @@ public function checkData()
             $this->setHasError(true);
             $this->setMessage(__('Item qty declaration error'));
         }
+    }
 
+    /**
+     * Checking item data
+     *
+     * @return $this
+     */
+    public function checkData()
+    {
+        $this->setQuantity();
         try {
             $this->getProduct()->getTypeInstance()->checkProductBuyState($this->getProduct());
         } catch (\Magento\Framework\Exception\LocalizedException $e) {

app/code/Magento/Quote/Model/ResourceModel/Quote/Item/Collection.php

@@ -293,6 +293,8 @@ protected function _assignProducts(): self
                 $item->setQtyOptions($qtyOptions)->setProduct($product);
                 if ($this->config->isEnabled()) {
                     $item->checkData();
+                } else {
+                    $item->setQuantity();
                 }
             }
         }