planner: change the cascades explain test as explain with brief format.

[AilinKid]

What problem does this PR solve?

Issue Number: ref #51664

Problem Summary:

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.

None

[tiprow]

Hi @AilinKid. Thanks for your PR.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.7645%. Comparing base (513bfeb) to head (d74be1d).
Report is 53 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #59745        +/-   ##
================================================
+ Coverage   73.0188%   73.7645%   +0.7456%     
================================================
  Files          1694       1701         +7     
  Lines        468298     478601     +10303     
================================================
+ Hits         341946     353038     +11092     
+ Misses       105335     104546       -789     
  Partials      21017      21017                

Flag	Coverage Δ
integration	43.2244% <ø> (?)
unit	72.6735% <ø> (+0.4610%)	⬆️

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

Components	Coverage Δ
dumpling	52.6910% <ø> (ø)
parser	∅ <ø> (∅)
br	44.6542% <ø> (-0.5458%)	⬇️

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-02-25 08:38:02.26365681 +0000 UTC m=+345030.216815075: ☑️ agreed by hawkingrei.
• 2025-02-25 09:35:00.381450097 +0000 UTC m=+348448.334608363: ☑️ agreed by qw4990.

[hawkingrei]

/retest