json: fix the issue that two arrays are merged but not append in JSON_ARRAY_APPEND.

[YangKeao]

What problem does this PR solve?

Issue Number: close #59465

Problem Summary:

Previously, JSON_ARRAY_APPEND('[1]', '$', '[2,3]') will give [1,2,3], which is not expected. It's because in TiDB the JSON_ARRAY_APPEND shared the same implementation with JSON_MERGE. To fix this issue, we should wrap the new item with an array when passing it to the merge logic.

What changed and how does it work?

Wrap the new item with array before re-using the merge logic.

Check List

Tests

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

  • I checked and no code files have been changed.

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.6191%. Comparing base (a116b4e) to head (11c0871).
Report is 10 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #59688        +/-   ##
================================================
+ Coverage   72.9684%   73.6191%   +0.6507%     
================================================
  Files          1697       1697                
  Lines        468907     470323      +1416     
================================================
+ Hits         342154     346248      +4094     
+ Misses       105690     103083      -2607     
+ Partials      21063      20992        -71     

Flag	Coverage Δ
integration	42.7797% <100.0000%> (?)
unit	72.4337% <100.0000%> (+0.2536%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	52.6910% <ø> (ø)
parser	∅ <ø> (∅)
br	45.1304% <ø> (+0.0282%)	⬆️

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: xhebox, XuHuaiyu

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Needs approval from an approver in each of these files:

• OWNERS [XuHuaiyu,xhebox]
• pkg/expression/OWNERS [XuHuaiyu]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-02-21 07:49:48.012299339 +0000 UTC m=+1206830.408521400: ☑️ agreed by xhebox.
• 2025-02-25 07:37:50.737846229 +0000 UTC m=+341418.691004495: ☑️ agreed by XuHuaiyu.

[YangKeao]

/retest