planner: simplify the indexJoinBuildHelper structure

[qw4990]

What problem does this PR solve?

Issue Number: ref #54057

Problem Summary: planner: simplify the indexJoinBuildHelper structure

What changed and how does it work?

ONLY REFACTORYING, NO LOGICAL CHANGE.

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 @qw4990. Thanks for your PR.

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[hawkingrei]

/ok-to-test

[codecov]

Codecov Report

Attention: Patch coverage is 90.90909% with 6 lines in your changes missing coverage. Please review.

Project coverage is 74.0080%. Comparing base (0ad2ca6) to head (6ec3754).
Report is 1 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #55079        +/-   ##
================================================
+ Coverage   72.8125%   74.0080%   +1.1955%     
================================================
  Files          1561       1561                
  Lines        438809     438959       +150     
================================================
+ Hits         319508     324865      +5357     
+ Misses        99605      93936      -5669     
- Partials      19696      20158       +462     

Flag	Coverage Δ
integration	28.0401% <31.8181%> (?)
unit	71.6704% <90.9090%> (-0.1411%)	⬇️

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

Components	Coverage Δ
dumpling	52.9567% <ø> (ø)
parser	∅ <ø> (∅)
br	52.5221% <ø> (+6.6254%)	⬆️

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hawkingrei, time-and-fate

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• pkg/planner/OWNERS [hawkingrei,time-and-fate]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-07-31 07:22:58.888579334 +0000 UTC m=+340495.168627396: ☑️ agreed by hawkingrei.
• 2024-07-31 07:23:08.021079101 +0000 UTC m=+340504.301127169: ☑️ agreed by time-and-fate.