Fix issue with duplicate title tags in blockbase (#6019)

Adding `title-tag` theme support is redundant in block themes. See
https://github.com/Automattic/themes/issues/5702 for full discussion.

blockbase/functions.php

@@ -17,9 +17,6 @@ if ( ! function_exists( 'blockbase_support' ) ) :
 		// Add support for post thumbnails.
 		add_theme_support( 'post-thumbnails' );
 
-		// Declare that there are no <title> tags and allow WordPress to provide them
-		add_theme_support( 'title-tag' );
-
 		// Experimental support for adding blocks inside nav menus
 		add_theme_support( 'block-nav-menus' );
 
@@ -189,4 +186,4 @@ require get_template_directory() . '/inc/block-patterns.php';
 // Add the child theme patterns if they exist.
 if ( file_exists( get_stylesheet_directory() . '/inc/block-patterns.php' ) ) {
 	require_once get_stylesheet_directory() . '/inc/block-patterns.php';
-}
+}