Editor: Revert the new default rendering mode for Pages.

This fully reverts changes from #61811 while leaving infrastructure in place for consumers to enable different default rendering modes for their post types.

Props mamaduka, joemcgill, mtdkei.
Fixes #63139.

git-svn-id: https://develop.svn.wordpress.org/trunk@60076 602fd350-edb4-49c9-b593-d223f7449a82

Author: Mamaduka

src/wp-includes/default-filters.php

@@ -565,7 +565,6 @@
 
 // Post.
 add_action( 'init', 'create_initial_post_types', 0 ); // Highest priority.
-add_action( 'init', 'wp_set_editor_default_mode', 1 ); // Run after registering post types.
 add_action( 'admin_menu', '_add_post_type_submenus' );
 add_action( 'before_delete_post', '_reset_front_page_settings_for_post' );
 add_action( 'wp_trash_post', '_reset_front_page_settings_for_post' );

src/wp-includes/post.php

@@ -8524,14 +8524,3 @@ function wp_create_initial_post_meta() {
 		)
 	);
 }
-
-/**
- * Sets the default editor mode based on support for block templates.
- *
- * @since 6.8.0
- */
-function wp_set_editor_default_mode() {
-	if ( wp_is_block_theme() && current_theme_supports( 'block-templates' ) ) {
-		add_post_type_support( 'page', 'editor', array( 'default-mode' => 'template-locked' ) );
-	}
-}