[Backport] Number of Lines in a Street Address not setting to default when you checked Use system value

Author: XxXgeoXxX

app/code/Magento/Customer/Model/Config/Backend/Address/Street.php

@@ -87,15 +87,20 @@ public function afterDelete()
     {
         $result = parent::afterDelete();
 
-        if ($this->getScope() == \Magento\Store\Model\ScopeInterface::SCOPE_WEBSITES) {
-            $attribute = $this->_eavConfig->getAttribute('customer_address', 'street');
-            $website = $this->_storeManager->getWebsite($this->getScopeCode());
-            $attribute->setWebsite($website);
-            $attribute->load($attribute->getId());
-            $attribute->setData('scope_multiline_count', null);
-            $attribute->save();
-        }
+        $attribute = $this->_eavConfig->getAttribute('customer_address', 'street');
+        switch ($this->getScope()) {
+            case \Magento\Store\Model\ScopeInterface::SCOPE_WEBSITES:
+                $website = $this->_storeManager->getWebsite($this->getScopeCode());
+                $attribute->setWebsite($website);
+                $attribute->load($attribute->getId());
+                $attribute->setData('scope_multiline_count', null);
+                break;
 
+            case ScopeConfigInterface::SCOPE_TYPE_DEFAULT:
+                $attribute->setData('multiline_count', 2);
+                break;
+        }
+        $attribute->save();
         return $result;
     }
 }