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, still not sure why empty copr addr appeared.

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. 

[yibin87]

/hold

[windtalker]

lgtm

[yibin87]

/unhold

[yibin87]

/test unit-test

[tiprow]

@yibin87: No presubmit jobs available for pingcap/tidb@release-6.1

In response to this:

/test unit-test

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-12-16 04:06:32.930061319 +0000 UTC m=+843383.018863855: ☑️ agreed by windtalker.
• 2024-12-16 05:00:19.858444625 +0000 UTC m=+846609.947247167: ☑️ agreed by hawkingrei.

[yibin87]

/test unit-test

[tiprow]

@yibin87: No presubmit jobs available for pingcap/tidb@release-6.1

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.