Obsolete option meta_include_file

Fixes #23573

config_defaults_inc.php

@@ -3406,12 +3406,6 @@
  */
 $g_css_rtl_include_file = 'rtl.css';
 
-/**
- * meta tags
- * @global string $g_meta_include_file
- */
-$g_meta_include_file = '';
-
 /**
  * A flag that indicates whether to use CDN (content delivery networks) for loading
  * javascript libraries and their associated CSS.  This improves performance for
@@ -4279,7 +4273,7 @@
 	'language_auto_map', 'fallback_language', 'login_method', 'plugins_enabled', 'session_handler',
 	'session_save_path', 'session_validation', 'show_detailed_errors', 'show_queries_count',
 	'stop_on_errors', 'version_suffix', 'debug_email',
-	'fileinfo_magic_db_file', 'css_include_file', 'css_rtl_include_file', 'meta_include_file',
+	'fileinfo_magic_db_file', 'css_include_file', 'css_rtl_include_file',
 	'file_type_icons', 'path', 'short_path', 'absolute_path', 'core_path',
 	'class_path','library_path', 'language_path', 'absolute_path_default_upload_folder',
 	'ldap_simulation_file_path', 'plugin_path', 'bottom_include_page', 'top_include_page',
@@ -4496,7 +4490,6 @@
 	'max_lost_password_in_progress_count',
 	'mentions_enabled',
 	'mentions_tag',
-	'meta_include_file',
 	'min_refresh_delay',
 	'minimum_sponsorship_amount',
 	'monitor_add_others_bug_threshold',

core/obsolete.php

@@ -211,3 +211,6 @@
 
 # changes in 2.8.0
 config_obsolete( 'inline_file_exts' );
+
+# changes in 2.9.0
+config_obsolete( 'meta_include_file' );

docbook/Admin_Guide/en-US/config/html.xml

@@ -102,14 +102,6 @@
 				<para>Set this to point to the RTL CSS file of your choice.</para>
 			</listitem>
 		</varlistentry>
-		<varlistentry>
-			<term>$g_meta_include_file</term>
-			<listitem>
-				<para>Set this to point to the META tag file of your
-					choice.
-				</para>
-			</listitem>
-		</varlistentry>
 		<varlistentry>
 			<term>$g_cdn_enabled</term>
 			<listitem>