Update the diagg multi_host script to auto lunch proxy

[mrjunwan-lang]

Description

1. Update the diagg multi_host script to auto lunch proxy
2. Delay the p2p_server start to avoid jax device status race condition

Tests

Please describe how you tested this change, and include any instructions and/or
commands to reproduce.

Checklist

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• I have performed a self-review of my code.
• I have necessary comments in my code, particularly in hard-to-understand areas.
• I have made or will make corresponding changes to any relevant documentation.

[github-actions]

Description

Start with a short description of what the PR does and how this is a change from
the past.

The rest of the description includes relevant details and context, examples:

• why is this change being made,
• the problem being solved and any relevant context,
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FIXES: b/123456
FIXES: #123456

Tests

Please describe how you tested this change, and include any instructions and/or
commands to reproduce.

Checklist

Before submitting this PR, please make sure:

• I have performed a self-review of my code.
• I have necessary comments in my code, particularly in hard-to-understand areas.
• I have made or will make corresponding changes to any relevant documentation.

[jcyang43]

Hi @mrjunwan-lang, I think this may have broken one of the unit tests (link). Can you PTAL? Thanks