planner: add some output when a flaky test fails

[winoros]

What problem does this PR solve?

Issue Number: close #xxx

Problem Summary:

This test is unstable in CI.

What changed and how does it work?

Add some output when it fails, and try to make it stable later.

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 ✅

Project coverage is 74.2552%. Comparing base (56710ae) to head (e2af715).
Report is 11 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #54980        +/-   ##
================================================
- Coverage   74.8246%   74.2552%   -0.5694%     
================================================
  Files          1559       1565         +6     
  Lines        363983     445338     +81355     
================================================
+ Hits         272349     330687     +58338     
- Misses        72047      94300     +22253     
- Partials      19587      20351       +764     

Flag	Coverage Δ
integration	49.4476% <ø> (?)
unit	71.6317% <ø> (-3.1801%)	⬇️

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

Components	Coverage Δ
dumpling	52.9567% <ø> (-2.2327%)	⬇️
parser	∅ <ø> (∅)
br	52.5555% <ø> (+4.8441%)	⬆️

[hawkingrei]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hawkingrei, qw4990

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Needs approval from an approver in each of these files:

• OWNERS [hawkingrei,qw4990]
• pkg/planner/OWNERS [hawkingrei,qw4990]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-07-27 19:12:57.824860521 +0000 UTC m=+37494.104908589: ☑️ agreed by hawkingrei.
• 2024-07-29 13:59:07.176995631 +0000 UTC m=+191463.457043700: ☑️ agreed by qw4990.