If a test requires Galera but it is not available, it is now skipped. All
tests that explicitly use the `test.galera` member as well as all tests
that use a Galera configuration now require that Galera is present.
As the wait_for_monitor function guarantees that the monitor notices the
state change, we can skip the replication fixing which was somewhat
superficial in the first place.
The `MYSQL_ROW row` variable was being overwritten by the extra query done
by the SST method detection code. Moving it into its own function prevents
this and makes the code significantly easier to comprehend.
Added a test case that reproduced the problem (MaxScale crashed) and
verifies that the patch fixes the problem.
