perf: enable HybridEP in H100/B200 performance recipes

[seonjinn]

Dependency

Depends on #3436. Do not merge this PR before #3436. The dependency-only diff will disappear after #3436 lands.

Summary

• Enable HybridEP in canonical 8-GPU MoE performance recipes for H100/B200 systems.
• Set the x86 topology explicitly to ranks/domain 8, NVLink domain 8, MNNVL disabled, and combine chunk 128.
• Set explicit GB200 topology for HybridEP 4-GPU recipes while leaving dense and non-HybridEP 4-GPU recipes unchanged.
• Validate the effective topology and emit one rank-zero diagnostic line during Megatron policy setup.

Testing

• Resolved performance recipe tests: 45 passed.
• Ruff, compileall, uv lock check, and git diff check passed.
• Linux MCore and H100/B200/GB200 server validation is in progress; job evidence will be added.

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[seonjinn]

/ok to test 67a4b3d

[seonjinn]

/ok to test 67a4b3d

[seonjinn]

/ok to test 0480dc6