Remove a11y script module

This script module requires an additional change that will be landed
separately before it can be landed.

See WordPress/gutenberg#65380.

tools/webpack/shared.js

@@ -103,7 +103,6 @@ const MODULES = [
 	'@wordpress/interactivity-router',
 ];
 const SCRIPT_AND_MODULE_DUAL_PACKAGES = [
-	'@wordpress/a11y',
 	'@wordpress/block-library',
 ];
 const WORDPRESS_NAMESPACE = '@wordpress/';