parser: also reduce literal list with charset (#61484)

[ti-chi-bot]

This is an automated cherry-pick of #61484

What problem does this PR solve?

Issue Number: close #58447

Problem Summary: _charset ?, _charset ?, i.e. list of literal with charset will be converted to ...

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.

Generate same digest for SQLs with `_charset(xxx), _charset(xxx2),...`

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Please upload report for BASE (release-8.1@acbf252). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-8.1     #62185   +/-   ##
================================================
  Coverage               ?   71.4295%           
================================================
  Files                  ?       1469           
  Lines                  ?     425968           
  Branches               ?          0           
================================================
  Hits                   ?     304267           
  Misses                 ?     101179           
  Partials               ?      20522           

Flag	Coverage Δ
unit	71.4295% <100.0000%> (?)

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

Components	Coverage Δ
dumpling	52.9656% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	41.6276% <0.0000%> (?)

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: tangenta, YangKeao

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• pkg/parser/OWNERS [tangenta]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-07-07 02:41:55.290402218 +0000 UTC m=+1881168.013581197: ☑️ agreed by YangKeao.
• 2025-07-07 02:46:40.890916437 +0000 UTC m=+1881453.614095440: ☑️ agreed by tangenta.

[xhebox]

/retest

[xhebox]

/retest

[xhebox]

/retest