SOLR-18262 Re-brand to Solr Orbit

[janhoy]

Renames the product from Apache Solr Benchmark to Apache Solr Orbit across the entire
codebase, as tracked in SOLR-18262.
The osbenchmark Python package folder rename is deferred to a separate follow-up task.

What changed

• CLI entry points: solr-benchmark → solr-orbit, solr-benchmarkd → solr-orbitd (setup.py, benchmark, benchmarkd wrapper scripts)
• PyPI package name: solr-benchmark → solr-orbit in setup.py and osbenchmark/version.py
• User config directory: ~/.solr-benchmark → ~/.solr-orbit (osbenchmark/paths.py, test_run_orchestrator.py, solr_provisioner.py)
• Default workloads repository: github.com/janhoy/solr-benchmark-workloads → github.com/apache/solr-orbit-workloads (both .ini config files)
• GitHub repository URLs: all github.com/janhoy/solr-benchmark references updated to github.com/apache/solr-orbit
• Documentation site URL: janhoy.github.io/solr-benchmark → apache.github.io/solr-orbit (docs/_config.yml and all doc pages)
• Docker image: group name, WORKDIR, volume path, and all LABEL fields updated in docker/Dockerfile
• Product name strings: Apache Solr Benchmark / Solr Benchmark replaced throughout Python source, CLI help text, log messages, and test fixtures (111 files total)
• Governance and guide files: NOTICE, CONTRIBUTING.md, DEVELOPER_GUIDE.md, PYTHON_SUPPORT_GUIDE.md, AGENTS.md, and CREATE_WORKLOAD_GUIDE.md updated
• Documentation site (~52 Markdown files under docs/): all name and URL references updated

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Pull request overview

Copilot reviewed 111 out of 111 changed files in this pull request and generated 2 comments.

[epugh]

There will be plenty of small tweaks and fixes but Lgtm