MDEV-4750: Fix a number of test failures in EXPLAIN outputs

  caused by weird behavior in innodb's persistent stats
- Run the testsuite without innodb persistent stats

mysql-test/mysql-test-run.pl

@@ -5306,6 +5306,8 @@ sub mysqld_arguments ($$$) {
   mtr_add_arg($args, "--loose-debug-sync-timeout=%s",
               $opt_debug_sync_timeout) unless $opt_user_args;
 
+  # MariaDB 10.0: disable innodb persistent statistics
+  mtr_add_arg($args, "--skip-innodb-stats-persistent");
   return $args;
 }