(Improvement) Remove CQL binary protocol v3

[mykaul]

No one needs it anymore. Any reasonable version of Cassandra and ScyllaDB support CQL binary protocol v4 (or higher).

This also assume that we test against Cassandra 2.2 or above, so removed some <= 2.1 items.

Pre-review checklist

• I have split my patch into logically separate commits.
• All commit messages clearly explain what they change and why.
• I added relevant tests for new features and bug fixes.
• All commits compile, pass static checks and pass test.
• PR description sums up the changes and reasons why they should be introduced.
• I have provided docstrings for the public items that I want to introduce.
• I have adjusted the documentation in ./docs/source/.
• I added appropriate Fixes: annotations to PR description.

[mykaul]

I'm very proud of:

+472 −1,193 

[Lorak-mmk]

@mykaul Could you please discuss next steps for that with @roydahan ?
On last team call we raised the idea to remove protocol v3, first from matrix, then from driver and scylla.
Roy's concern is that it should be done with a proper depreciation announcements, making sure then no one uses it etc.

[mykaul]

@mykaul Could you please discuss next steps for that with @roydahan ? On last team call we raised the idea to remove protocol v3, first from matrix, then from driver and scylla. Roy's concern is that it should be done with a proper depreciation announcements, making sure then no one uses it etc.

In theory, you are right. In practice - Scylla uses and supports v4, who is going to use v3 against it? and if they do, why would they upgrade their driver? but generally - fair point - we need to deprecate it in docs or something first. I'll get it to 2026.1 hopefully.