Do minor improvements to monitor tests

The mm test was on the heavy side and the workload can be reduced for the
sake of testing only the functionality.

The mm_mysqlmon test did not check the initial state of the
server. Although not necessary, adding it will help detect test failures
caused by broken replication.

mxs1457_ignore_deleted did not stop the monitors before breaking the
replication and attempting to use MaxScale. As the test expects
authentication to work regardless of the actual state of the servers, the
monitors need to be disabled before a query is attempted.

maxscale-system-test/mxs1457_ignore_deleted.cpp

@@ -17,6 +17,11 @@ int main(int argc, char *argv[])
     test.repl->sync_slaves();
     test.repl->close_connections();
 
+    /**
+     * The monitor needs to be stopped before the slaves are stopped to prevent
+     * it from detecting the broken replication.
+     */
+    test.ssh_maxscale(true, "maxadmin shutdown monitor \"MySQL Monitor\"");
     // Stop slaves and drop the user on the master
     test.repl->stop_slaves();
     test.repl->connect();