[Feature][eplb] add verify ep or tp or dp

[lengrongfu]

Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)". [Feature]: Add Enable EPLB condition #20669
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.

Because if not use tp or dp or ep, so enable eplb whether meaningful.

Purpose

Test Plan

Test Result

(Optional) Documentation Update

[gemini-code-assist]

Code Review

This pull request adds validation checks for Expert Parallelism Load Balancing (EPLB) configuration. The checks ensure that when EPLB is enabled, expert parallelism is also enabled, and both tensor and data parallelism are configured with more than one worker. I suggested improving the clarity of the validation error messages to provide more specific guidance to the user.

[github-actions]

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