SOLR-17576: Remove deprecated master/slave support in ReplicationHandler

[epugh]

https://issues.apache.org/jira/browse/SOLR-17576

Description

Remove deprecated terms.

Solution

Deletes

Tests

Existing tests

Checklist

Please review the following and check all that apply:

• I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
• I have created a Jira issue and added the issue ID to my pull request title.
• I have given Solr maintainers access to contribute to my PR branch. (optional but recommended, not available for branches on forks living under an organisation)
• I have developed this patch against the main branch.
• I have run ./gradlew check.
• I have added tests for my changes.
• I have added documentation for the Reference Guide

[gus-asf]

I'm confused. There seems to be a lot more in this than just touching up terminology to match the Leader/Follower?

[gus-asf]

some of the trivial stuff like spelling fixes isn't of concern, but I assume some of the larger deletions are removals of unused methods... I think that type of thing should be it's own change so that the reason for removal can be clearer to anyone who might have used it in 3rd party code or forks of our repo...

[epugh]

@gus-asf unfortuantly, I have to agree with you.... I'm going to redo this PR to seperate out the code cleanups from the deprecations. I just read @dsmiley link about "how to maintain forks" and it really pushed the atomicity of PR's. It kills me to be going through code and seeing obvious errors and problems and NOT fix them. The next time, I might try having two copies of Solr in seperate directories, and try to keep "annonying code issue fixes" on one, and the thrust of whatever I am doing on the other....

[epugh]

I've removed the extra refactorings and created a new issue https://issues.apache.org/jira/browse/SOLR-17579 to track that (and remind me!)