test to stall for slave_net_timeout and cause some test case fail

mysql-test/include/have_log_bin.inc:
  remove reset master, which can cause some test to stall for slave_net_timeout and cause some test case fail
mysql-test/r/mysqlbinlog_base64.result:
  update result
mysql-test/t/mysqlbinlog_base64.test:
  Add reset master to make sure binlog is clean when the test case start