Revert "Gutenberg plugin: Override core classic theme styles (#73580)"

This reverts commit 9fd3035.

Author: t-hamano

lib/client-assets.php

@@ -397,16 +397,6 @@ function gutenberg_register_packages_styles( $styles ) {
 	);
 	$styles->add_data( 'wp-block-library-theme', 'rtl', 'replace' );
 
-	gutenberg_override_style(
-		$styles,
-		'classic-theme-styles',
-		gutenberg_url( 'build/styles/block-library/classic.css' ),
-		array(),
-		$version
-	);
-	$styles->add_data( 'classic-theme-styles', 'rtl', 'replace' );
-	$styles->add_data( 'classic-theme-styles', 'path', gutenberg_dir_path() . 'build/styles/block-library/classic.css' );
-
 	gutenberg_override_style(
 		$styles,
 		'wp-list-reusable-blocks',