expression: make count distinct multi column aware of new collation (#27111)

[ti-srebot]

cherry-pick #27111 to release-4.0
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# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/27830

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git push git@github.com:ti-srebot/tidb.git pr/27830:release-4.0-08995d915d3d

---

What problem does this PR solve?

Issue Number: close #27091

Problem Summary:

As the issue described.

What is changed and how it works?

Proposal: xxx

What's Changed:

How it Works:

Use the collation info when calling UpdatePartialResult in countOriginalWithDistinct and approxCountDistinctOriginal

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 bug that count disctinct on multi-columns return wrong result when new collation is on.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• qw4990
• wjhuang2016

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[ti-srebot]

/run-all-tests

[ti-srebot]

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

[windtalker]

/run-check_dev

[zhouqiang-cl]

/merge

[ti-chi-bot]

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

Commit hash: 7abbc1e

[ti-chi-bot]

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