Editor: Update WordPress packages to use with WordPress 5.8

In the response to the discussion during the Dev Chat, I'm doing a first pass to keep WordPress packages up to date in the WordPress 5.8 release cycle.

See https://github.com/WordPress/wordpress-develop/pull/1176 for more details.

Props youknowriad, aristath, andraganescu.
See #52991.



git-svn-id: https://develop.svn.wordpress.org/trunk@50761 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/blocks/index.php

@@ -52,7 +52,6 @@ function register_core_block_types_from_metadata() {
 		'separator',
 		'social-links',
 		'spacer',
-		'subhead',
 		'table',
 		'text-columns',
 		'verse',