Make the MDEV-14874 test case more robust

mysql-test/suite/mariabackup/huge_lsn.result

@@ -2,10 +2,11 @@
 # MDEV-13416 mariabackup fails with EFAULT "Bad Address"
 #
 call mtr.add_suppression("InnoDB: New log files created");
-FOUND /InnoDB: .*started; log sequence number 17596481010700/ in mysqld.1.err
+FOUND /InnoDB: New log files created, LSN=175964\d{8}/ in mysqld.1.err
 CREATE TABLE t(i INT) ENGINE INNODB;
 INSERT INTO t VALUES(1);
 # xtrabackup backup
+SET GLOBAL innodb_flush_log_at_trx_commit=1;
 INSERT INTO t VALUES(2);
 # xtrabackup prepare
 # shutdown server

mysql-test/suite/mariabackup/huge_lsn.test

@@ -28,8 +28,9 @@ EOF
 --remove_files_wildcard $MYSQLD_DATADIR ib_logfile*
 
 --source include/start_mysqld.inc
+let SEARCH_RANGE= -50000;
 let SEARCH_FILE= $MYSQLTEST_VARDIR/log/mysqld.1.err;
---let SEARCH_PATTERN= InnoDB: .*started; log sequence number 17596481010700
+--let SEARCH_PATTERN= InnoDB: New log files created, LSN=175964\d{8}
 --source include/search_pattern_in_file.inc
 
 CREATE TABLE t(i INT) ENGINE INNODB;
@@ -40,6 +41,7 @@ let $targetdir=$MYSQLTEST_VARDIR/tmp/backup;
 --disable_result_log
 exec $XTRABACKUP --defaults-file=$MYSQLTEST_VARDIR/my.cnf --backup --target-dir=$targetdir;
 --enable_result_log
+SET GLOBAL innodb_flush_log_at_trx_commit=1;
 INSERT INTO t VALUES(2);
 echo # xtrabackup prepare;
 --disable_result_log