disable an old test

@@open_files_limit now behaves differenly and cannot
be used to skip the test anymore.

mysql-test/disabled.def

@@ -15,3 +15,4 @@ read_many_rows_innodb    : Bug#11748886 2010-11-15 mattiasj report already exist
 mysql_embedded           : Bug#12561297 2011-05-14 Anitha Dependent on PB2 changes - eventum#41836
 file_contents            : MDEV-6526 these files are not installed anymore
 lowercase_fs_on          : lower_case_table_names=0 is not an error until 10.1
+partition_open_files_limit : open_files_limit check broken by MDEV-18360