fix: [2.5] Decode unicode for json key in expression

[xiaocai2333]

issue: #38626

master pr: #38651

[czs007]

/approve
/lgtm

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: czs007, xiaocai2333

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [czs007]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.03%. Comparing base (7d46a8f) to head (9556b94).
Report is 1 commits behind head on 2.5.

Additional details and impacted files

@@             Coverage Diff             @@
##              2.5   #38653       +/-   ##
===========================================
+ Coverage   69.33%   81.03%   +11.69%     
===========================================
  Files         292     1381     +1089     
  Lines       26187   195094   +168907     
===========================================
+ Hits        18158   158098   +139940     
- Misses       8029    31427    +23398     
- Partials        0     5569     +5569     

Components	Coverage Δ
Client	78.26% <ø> (∅)
Core	69.33% <ø> (ø)
Go	83.01% <100.00%> (∅)

Files with missing lines	Coverage Δ
internal/parser/planparserv2/parser_visitor.go	86.05% <100.00%> (ø)
internal/parser/planparserv2/plan_parser_v2.go	86.91% <ø> (ø)
internal/parser/planparserv2/utils.go	87.10% <100.00%> (ø)

... and 1086 files with indirect coverage changes