PR #3197 adds generated markdown docs for MS MARCO prebuilt-index reproductions, but the current implementation is still fairly bespoke. Follow up by refactoring the doc generation path so it is more config-driven and can cover the remaining prebuilt-index reproduction configs.

Requested cleanup from review:

• Evaluate whether individual docgen templates are still needed, or whether the markdown can be generated directly from the reproduction YAML configs.
• Reduce duplication across the generateMsMarcoXReport methods in GenerateReproductionDocsFromPrebuiltIndexes2Test; these methods are structurally similar and should likely share a generic generator.
• Move hardcoded summary/table mappings into a static definition or into the YAML configs, rather than baking them into the Java generator logic.
• Add generated docs for BEIR and BRIGHT configs, which are present under src/main/resources/reproduce/from-prebuilt-indexes/configs but are not covered by the current generated markdown docs.

Acceptance criteria:

• Doc generation supports MS MARCO, BEIR, and BRIGHT prebuilt-index reproduction configs.
• Repeated report-generation logic is consolidated into a generic config-driven path where practical.
• Any remaining hardcoded mappings are minimal and clearly isolated.
• Generated docs are refreshed and covered by the existing doc generation test workflow.