BUG#19951: Race conditions in test wait_timeout.

Fix random failures in test 'wait_timeout' that depend on exact timing.

1. Force a reconnect initially if necessary, as otherwise slow startup
might have caused a connection timeout before the test can even start.

2. Explicitly disconnect the first connection to remove confusion about
which connection aborts from timeout, causing test failure.

mysql-test/r/wait_timeout.result

@@ -1,3 +1,7 @@
+select 0;
+0
+0
+flush status;
 select 1;
 1
 1