executor: fix query panic on INFORMATION_SCHEMA.CLUSTER_SLOW_QUERY with some slow query files (#54325)

[ti-chi-bot]

This is an automated cherry-pick of #54325

What problem does this PR solve?

Issue Number: close #54324

Problem Summary:

What changed and how does it work?

The old code does not handle all the cases well.
if i >= len(lines)-1 should be a typo, it should be something like if i >= len(chars)-1
And the simplified logic is just the same as this PR.

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 ✅

Please upload report for BASE (release-8.1@ae394c6). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-8.1     #54710   +/-   ##
================================================
  Coverage               ?   72.3133%           
================================================
  Files                  ?       1465           
  Lines                  ?     432729           
  Branches               ?          0           
================================================
  Hits                   ?     312921           
  Misses                 ?      99573           
  Partials               ?      20235           

Flag	Coverage Δ
unit	72.3133% <100.0000%> (?)

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

Components	Coverage Δ
dumpling	53.9957% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	40.8158% <0.0000%> (?)

[tiancaiamao]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: crazycs520, Defined2014

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• OWNERS [Defined2014,crazycs520]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-07-31 08:40:20.42009269 +0000 UTC m=+345136.700140760: ☑️ agreed by Defined2014.
• 2024-07-31 08:40:54.323613988 +0000 UTC m=+345170.603662058: ☑️ agreed by crazycs520.

[tiancaiamao]

/retest