Replace SimpleStrategy with NetworkTopologyStrategy across codebase

[roydahan]

ScyllaDB has dropped support for SimpleStrategy. Update all tests, examples, benchmarks, and management utilities to use NetworkTopologyStrategy instead, while preserving the SimpleStrategy class definition in the driver for backward compatibility with Cassandra clusters.

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.

[roydahan]

I see there is a PR that just got merged for that #830