Additionally filter out non nil empty values for country code

Author: RafaelKayumov

WooCommerce/Classes/ViewRelated/Orders/Order Details/Shipping Labels/WooShipping Create Shipping Labels/WooShipping Customs/WooShippingCustomsItemViewModel.swift

@@ -103,6 +103,7 @@ private extension WooShippingCustomsItemViewModel {
     func combineToPreselectCountry() {
         $originCountryCode
             .compactMap { $0 }
+            .filter { !$0.isEmpty }
             .first() /// Make sure to only handle the initial value
             .combineLatest($countries)
             .map { code, countries in