delete deprecated logoff_ms gflag in example folder

[leaf-potato]

What problem does this PR solve?

Issue Number: #2060

Problem Summary: logoff_ms gflag in example is not used.

What is changed and the side effects?

Changed: delete deprecated logoff_ms gflag in example folder.

Side effects:

• Performance effects(性能影响): no

• Breaking backward compatibility(向后兼容性): yes

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Check List:

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