expression: fix panic in upper() and lower() func. (#32505)

[ti-srebot]

cherry-pick #32505 to release-5.4
You can switch your code base to this Pull Request by using git-extras:

# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/32512

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/tidb.git pr/32512:release-5.4-14bedf3ee5a2

---

What problem does this PR solve?

Issue Number: close #32488

Problem Summary: Columns.SetRaw can't be used in upper() and lower(). Because the result of upper() and lower() may not same as before.

What is changed and how it works?

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

fix panic in upper() and lower() func

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• tangenta
• xiongjiwei

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[ti-srebot]

/run-all-tests

[ti-srebot]

@Defined2014 you're already a collaborator in bot's repo.

[tiancaiamao]

PTAL @tangenta @xiongjiwei

[tiancaiamao]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 4270555

[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/c5787c7e1408bdf26de05bdd0231a78524fed07c

[ti-chi-bot]

@ti-srebot: This cherry pick PR is for a release branch and has not yet been approved by release team.
Adding the do-not-merge/cherry-pick-not-approved label.

To merge this cherry pick, it must first be approved by the collaborators.

AFTER it has been approved by collaborators, please ping the release team in a comment to request a cherry pick review.

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