Problem:
========
There is a race condition in binlog.binlog_checkpoint between the
binlog background thread creating a binlog checkpoint event, and the
connection thread binlogging a query event for creating a table.
Because the test outputs the events for validation, the order
between these two events can be different, resulting in a failed
test.

Solution:
========
Instead of outputting the binlog events, use assert_grep to validate
the content of the binlog is correct.

Reviewed By:
============
Andrei Elkin <andrei.elkin@mariadb.com>