Stop repair scheduler if two major versions are detected

[himanshujindal]

Do not allow repair scheduler to run repair if two major versions are detected. This can happen during major version upgrade, and we don't want repair to run since the streaming data for repair can be incompatible across major versions.

Users can override this using a cassandra yaml config if they want to.

Also, this does not affect minor version upgrades, or repair jobs run manually.

https://issues.apache.org/jira/browse/CASSANDRA-20048
#4304

Thanks for sending a pull request! Here are some tips if you're new here:

• Ensure you have added or run the appropriate tests for your PR.
• Be sure to keep the PR description updated to reflect all changes.
• Write your PR title to summarize what this PR proposes.
• If possible, provide a concise example to reproduce the issue for a faster review.
• Read our contributor guidelines
• If you're making a documentation change, see our guide to documentation contribution

Commit messages should follow the following format:

<One sentence description, usually Jira title or CHANGES.txt summary>

<Optional lengthier description (context on patch)>

patch by <Authors>; reviewed by <Reviewers> for CASSANDRA-#####

Co-authored-by: Name1 <email1>
Co-authored-by: Name2 <email2>

The Cassandra Jira

[himanshujindal]

This follows from #4304. I had to remove the previous branch to perform a clean rebase on top of trunk.

CI run - https://pre-ci.cassandra.apache.org/job/cassandra/83/

[himanshujindal]

This follows from #4304. I messed up the command to force push the new branch onto the existing PR - so I had to create a new PR.

1. rebased all changes onto trunk
2. updated CHANGES.txt
3. CI run - CI run - https://pre-ci.cassandra.apache.org/job/cassandra/84

[himanshujindal]

Updated the commit correctly now

This follows from #4304. I messed up the command to force push the new branch onto the existing PR - so I had to create a new PR.

1. rebased all changes onto trunk
2. updated CHANGES.txt
3. CI run - CI run - https://pre-ci.cassandra.apache.org/job/cassandra/85

[himanshujindal]

Now correctly rebased as well. There is no diff between the two - just that the new commit is a rebase. So previous test run should be good - https://pre-ci.cassandra.apache.org/job/cassandra/85

I have also spun off a new run - https://pre-ci.cassandra.apache.org/job/cassandra/86/

[jaydeepkumar1984]

This PR has been a duplicate of #4304, and we can see that #4304 was already approved by @jaydeepkumar1984 and @tolbertam

[tolbertam]

Verrrrrry tiny nit: Recent Changes should go at the top instead the bottom of changes for a release.