[AMQ-8316] Remove unused BrokerService methods
This removes passiveSlave and waitForSlave which are no longer used
We probably should create a web page for 5.17.0 changes. This is going to remove config parameters from the XSD and generated xbean properties.
I'll create a parallel PR for that later this week.
@mattrpav , @jbonofre I created a pull on the website to begin collecting changes for 5.17 - https://github.com/apache/activemq-website/pull/63
@ehossack-aws it makes sense, thanks. I will take a look then.
Resuming review on this one.
It will be superseeded by another PR related to AMQ-9349