expression: uncomment pushdown for JSONUnquote expression (#24504)

[ti-srebot]

cherry-pick #24504 to release-4.0
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# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/25721

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git push git@github.com:ti-srebot/tidb.git pr/25721:release-4.0-bd8d3b1a8cfb

---

What problem does this PR solve?

Issue Number: close #24415

Problem Summary:

What is changed and how it works?

This PR tries to open the pushdown of JSONUnquote expression, by uncommenting it in the 'pushdown list'.

Related changes

• Related doc to change: remove json_unquote() from expressions-pushed-down.md docs#5564
• Need to cherry-pick to the release branch

Check List

Tests

• Integration test(the "idc-jenkins-ci-tidb/integration-copr-test"): https://github.com/tikv/copr-test/blob/master/push-down-test/sql/randgen/9_json.sql

Release note

• Enable the pushdown of builtin function json_unquote() to TiKV.

[ti-srebot]

/run-all-tests

[ti-srebot]

@bb7133 you're already a collaborator in bot's repo.

[zhouqiang-cl]

/merge

[ti-chi-bot]

@zhouqiang-cl: /merge in this pull request requires 2 approval(s).

In response to this:

/merge

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[guo-shaoge]

@wshwsh12 ptal

[ti-chi-bot]

[REVIEW NOTIFICATION]

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• guo-shaoge
• wshwsh12

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[zhouqiang-cl]

/merge

[ti-chi-bot]

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

Commit hash: 36c36ee

[ti-chi-bot]

@ti-srebot: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.