disable ps_protocol in log_tables test.

The log content is obviously different in two modes,
as Queries are translated into Prepare and Execute
commands. Thus we should use test only in one mode
to get the match with result.

mysql-test/t/log_tables.test

@@ -5,6 +5,7 @@
 # check that CSV engine was compiled in
 --source include/have_csv.inc
 
+--disable_ps_protocol
 use mysql;
 
 #
@@ -143,4 +144,5 @@ select "Mark that we woke up from TRUNCATE in the test"
 
 disconnect con2;
 disconnect con1;
+--enable_ps_protocol