MDEV-9077 - sys schema

Babysit Aria engine. Try to avoid random "Zerofilling moved file" messages
coming seemingly from trying to access sys_config table, mostly likely after
bootstrap.

scripts/sys_schema/tables/sys_config_data_57.sql

@@ -22,3 +22,5 @@ INSERT IGNORE INTO sys.sys_config (variable, value) VALUES
     ('diagnostics.allow_i_s_tables', 'OFF'),
     ('diagnostics.include_raw', 'OFF'),
     ('ps_thread_trx_info.max_length', 65535);
+
+FLUSH TABLES sys.sys_config;