docs: limit HCCL baseline to once per environment

[Kur0x]

Summary

• treat official HCCL Test as a one-time environment qualification instead of a per-task prerequisite
• define the environment identity and require retained results to be reused without rerunning on uncovered paths
• align the maintained MindSpeed debugging guide and recent Dispatch validation documents with the one-run policy

Validation

• git diff --check origin/main...HEAD
• searched active documentation for the superseded commands to run HCCL Test on every investigation
• documentation-only change; code, build, and NPU tests were not run

[chatgpt-codex-connector]

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