MDEV-24024 innodb.ibuf_not_empty failed in buildbot

Probably due to the changes to page flushing in MDEV-23399
(commit 7cffb5f) the command
CHECK TABLE would occasionally report a different number of rows
for the corrupted secondary index. (The reported number was 991
instead of 990 on one occasion.)

Let us map all numbers to 990 in the output. We only care that the
injected corruption will be detected.

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

@@ -68,6 +68,7 @@ EOF
 --let $restart_parameters= --innodb-force-recovery=6 --innodb-change-buffer-dump
 --source include/start_mysqld.inc
 
+--replace_regex /contains \d+ entries/contains 990 entries/
 check table t1;
 
 --source include/shutdown_mysqld.inc