feat: java example simplify (#14843)

[ti-chi-bot]

This is an automated cherry-pick of #14843

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What is the related PR or file link(s)?

• This PR is translated from:
• Other reference link(s): develop: improve python mysqlclient sample code doc #14902

Do your changes match any of the following descriptions?

• Delete files
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[Oreoxmt]

/approve

[ti-chi-bot]

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