Fix poc shutdown

[YuanTingHsieh]

Fix poc shutdown

Description

Fix poc shutdown

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Quick tests passed locally by running ./runtest.sh.
• In-line docstrings updated.
• Documentation updated.

[Copilot]

Pull Request Overview

This PR fixes the POC shutdown functionality by clarifying the shutdown methods used in different scenarios and removing outdated documentation related to deprecated SP (service provider) commands.

• Updates print statements to clarify whether shutdown uses FLARE API or stop_fl.sh script
• Removes documentation for deprecated SP-related commands (list_sp, get_active_sp, promote_sp)
• Cleans up migration documentation to remove references to removed SP commands

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
nvflare/tool/poc/poc_commands.py	Updates shutdown print statements to clarify shutdown method
docs/real_world_fl/operation.rst	Removes deprecated SP command documentation
docs/real_world_fl/migrating_to_flare_api.rst	Removes SP commands from migration table

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[yanchengnv]

See my comment about wait_for_system_shutdown.

[YuanTingHsieh]

/build