[ticket/16956] Remove router cache flag

The deferred purge will be used in the future instead. The cache flag in the
router only causes additional issues by trying to rebuild the routing
mid-request

PHPBB3-16956

phpBB/config/default/container/services.yml

@@ -116,7 +116,6 @@ services:
             - '@dbal.conn'
             - '@config'
             - '@filesystem'
-            - '@router'
             - '%tables.ext%'
             - '%core.root_path%'
             - '%core.php_ext%'