Only Set Collect Shipping Rates Once

+ Also set in Magento\Checkout\Model\Cart::save()
+ See: https://github.com/magento/magento2/blob/2.4-develop/app/code/Magento/Checkout/Model/Cart.php#L591

Author: pykettk

app/code/Magento/Checkout/Controller/Cart/EstimatePost.php

@@ -63,8 +63,7 @@ public function execute()
             ->setCity($city)
             ->setPostcode($postcode)
             ->setRegionId($regionId)
-            ->setRegion($region)
-            ->setCollectShippingRates(true);
+            ->setRegion($region);
         $this->cart->save();
         return $this->_goBack();
     }