This commit fixes all 1533 PHPCS errors that PHPCBF can fix automatically in the tests/ directory. Before this change there was a total of 3106 PHPCS errors in the WooCommerce repository and now there is 1573 errors.
WC core supports both integers and strings as values to the download ID but this is necessary to make the core unit tests pass when running them in the context of the custom product tables plugins. This plugin accepts only integers for the download ID.