add a note to automatic retry (#21927)

[ti-chi-bot]

This is an automated cherry-pick of #21927

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

• This PR is translated from:Fix outdated statement about TiDB's default transaction mode in optimistic-transaction.md docs-cn#21007
• Other reference link(s):Fix outdated statement about TiDB's default transaction mode in optimistic-transaction.md #21921

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• Delete files
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• Might cause conflicts after applied to another branch

[gemini-code-assist]

Summary of Changes

Hello @ti-chi-bot, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request updates the TiDB documentation regarding optimistic transactions, specifically focusing on the automatic retry mechanism. The changes aim to provide users with crucial information about when automatic retries are disabled by default, their impact on transaction isolation, and their deprecation in newer TiDB versions, ensuring the documentation accurately reflects current behavior and recommendations.

Highlights

• Documentation Update for Automatic Transaction Retry: A new note has been added to the optimistic-transaction.md documentation to provide clearer guidance on the automatic retry mechanism for transactions in TiDB.
• Clarification on Isolation Level Impact: The added note explicitly states that automatic transaction retries are disabled by default from TiDB v3.0.0 because they can potentially break the transaction isolation level.
• Deprecation of Optimistic Transaction Retries: The documentation now clearly indicates that automatic retries for optimistic transactions are no longer supported starting from TiDB v8.0.0.

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[gemini-code-assist]

Code Review

This pull request adds a helpful note to clarify the status of automatic retries in optimistic transactions. I've provided a couple of suggestions to improve the documentation further. One is a minor wording tweak for conciseness in the new note. The other is a more significant change to an adjacent paragraph to ensure the documentation is clear and not contradictory for users of different TiDB versions, especially given the new information about deprecation.

[hfxsd]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hfxsd

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