MDEV-8841 innodb_zip.innodb-create-options fails in buildbot

The real problem is that when innodb.xa_recovery test intentionally
crashes the server, system tables can be opened and marked as crashed,
and the next test in line gets blamed for the error which appears
in the error log.
Fixed by flushing the tables before crashing the server

mysql-test/suite/innodb/t/xa_recovery.test

@@ -6,6 +6,12 @@ if (`select plugin_auth_version <= "5.5.43-MariaDB-37.2" from information_schema
 # Embedded server does not support restarting.
 --source include/not_embedded.inc
 
+# MDEV-8841 - close tables opened by previous tests, 
+# so they don't get marked crashed when the server gets crashed
+--disable_query_log
+FLUSH TABLES;
+--enable_query_log
+
 CREATE TABLE t1 (a INT) ENGINE=InnoDB;
 INSERT INTO t1 VALUES (1);
 connect (con1,localhost,root);