is_existing_sku should check all post statuses except for trash

Fixes #14525

includes/data-stores/class-wc-product-data-store-cpt.php

@@ -802,7 +802,7 @@ class WC_Product_Data_Store_CPT extends WC_Data_Store_WP implements WC_Object_Da
 			FROM $wpdb->posts
 			LEFT JOIN $wpdb->postmeta ON ( $wpdb->posts.ID = $wpdb->postmeta.post_id )
 			WHERE $wpdb->posts.post_type IN ( 'product', 'product_variation' )
-			AND $wpdb->posts.post_status = 'publish'
+			AND $wpdb->posts.post_status != 'trash'
 			AND $wpdb->postmeta.meta_key = '_sku' AND $wpdb->postmeta.meta_value = '%s'
 			AND $wpdb->postmeta.post_id <> %d LIMIT 1
 		 ", wp_slash( $sku ), $product_id ) );