Reduce excessive sleeping in tests

Some of the tests waited for excessively long periods of time for changes
to propagate. With a one second monitor interval, a sleep of around five
seconds should be plenty enough for all monitor related changes to be
propagated to all systems.

maxscale-system-test/bug676.cpp

@@ -26,7 +26,7 @@ int main(int argc, char *argv[])
     test.stop_timeout();
 
     test.tprintf("Waiting until the monitor picks a new master");
-    sleep(20);
+    sleep(5);
 
     test.set_timeout(30);