planner: plan cache always check scheme valid in RC isolation level (#34523)

[ti-srebot]

cherry-pick #34523 to release-6.0
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# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/34620

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git push [email protected]:ti-srebot/tidb.git pr/34620:release-6.0-0703a64f76ba

---

Signed-off-by: you06 [email protected]

What problem does this PR solve?

Issue Number: close #34447

Problem Summary:

What is changed and how it works?

Plan cache always checks if the schema is stale in the RC isolation level because it should guarantee the index still exist in the latest schema.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

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[ti-srebot]

/run-all-tests

[ti-srebot]

@you06 you're already a collaborator in bot's repo.

[you06]

6.0 is not a LTS version, close this fix.