Product Gallery block: Fix 404 errors occurring on frontend (https://github.com/woocommerce/woocommerce-blocks/pull/10555)

* Prevent block from loading frontend scripts

* Fix issue with Product Gallery not being registered on the Editor

* Fix php cs error

plugins/woocommerce-blocks/src/BlockTypes/ProductGallery.php

@@ -20,4 +20,13 @@ class ProductGallery extends AbstractBlock {
 	protected function get_block_type_style() {
 		return null;
 	}
+
+	/**
+	 * It isn't necessary register block assets because it is a server side block.
+	 */
+	protected function register_block_type_assets() {
+		parent::register_block_type_assets();
+
+		return null;
+	}
 }