Fix binlog_trx_meta_data.test

Summary:
This test used to fail sometimes during purging binlogs because the
binlog to be purged was still being read by the slave. Added a slave sync to
avoid this.

Reviewed By: yashtc

Differential Revision: D8249786

fbshipit-source-id: a59ce8b

Author: abhinav04sharma

mysql-test/suite/rpl/include/binlog_trx_meta_data.inc

@@ -1,5 +1,7 @@
 # Init
 connection master;
+sync_slave_with_master;
+connection master;
 flush logs;
 let $master_last_log = query_get_value("SHOW MASTER STATUS", "File", 1);
 eval purge binary logs to '$master_last_log';