executor: Fix the parse problematic slow log panic issue due to empty value string (#58258)

[ti-chi-bot]

This is an automated cherry-pick of #58258

What problem does this PR solve?

Issue Number: close #58147

Problem Summary:
Handle uncommon empty value string case in slow log. Checked that queries for system tables, like stats_meta, will generate empty copr address.

What changed and how does it work?

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.

Fix the issue that queries for slow log may fail when some item's value is empty. 

[windtalker]

lgtm

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hawkingrei, windtalker

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• OWNERS [hawkingrei,windtalker]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-12-16 04:03:57.267259365 +0000 UTC m=+843227.356061907: ☑️ agreed by hawkingrei.
• 2024-12-16 04:04:02.300359576 +0000 UTC m=+843232.389162119: ☑️ agreed by windtalker.

[yibin87]

/hold

[yibin87]

/unhold

[yibin87]

/run mysql-test

[yibin87]

/test mysql-test

[tiprow]

@yibin87: No presubmit jobs available for pingcap/tidb@release-8.1

In response to this:

/test mysql-test

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[yibin87]

/test unit-test

[tiprow]

@yibin87: No presubmit jobs available for pingcap/tidb@release-8.1

In response to this:

/test unit-test

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 kubernetes-sigs/prow repository.

[codecov]

Codecov Report

Attention: Patch coverage is 69.23077% with 4 lines in your changes missing coverage. Please review.

Please upload report for BASE (release-8.1@9ffb182). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-8.1     #58274   +/-   ##
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  Coverage               ?   71.1940%           
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  Files                  ?       1468           
  Lines                  ?     423745           
  Branches               ?          0           
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  Hits                   ?     301681           
  Misses                 ?     101539           
  Partials               ?      20525           

Flag	Coverage Δ
unit	71.1940% <69.2307%> (?)

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	41.1961% <0.0000%> (?)