stmtsummary: fix issue of concurrent map read and write (#35367)

[ti-srebot]

cherry-pick #35367 to release-5.2
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/35383

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git push git@github.com:ti-srebot/tidb.git pr/35383:release-5.2-f8a00f33e8e6

---

Signed-off-by: crazycs520 crazycs520@gmail.com

What problem does this PR solve?

Issue Number: close #35340

Problem Summary: statements_summary has concurrent map read and write

What is changed and how it works?

Check List

Tests

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

Release note

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None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• djshow832
• tangenta

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[ti-srebot]

/run-all-tests

[ti-srebot]

@crazycs520 you're already a collaborator in bot's repo.

[crazycs520]

/merge

[ti-chi-bot]

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

Commit hash: 81e44ee

[crazycs520]

/merge

[ti-chi-bot]

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