The avrorouter failed to detect ALTER TABLE statements which caused a
regression. Extended the alter table tests to parse the JSON for more
strict validation of test results.
The timeout is hit very often if the cluster fixing takes some time. This
causes false positives so the timeout should be stopped before attempting
to fix the cluster.
The slave part of the binlogrouter replication can be ignored for
avrorouter tests. This will speed up the testing by skipping the
unnecessary restarting and configuration of slave servers.
