planner: fix index merge intersection case will have redundant partial path (#50495)

[ti-chi-bot]

This is an automated cherry-pick of #50495

What problem does this PR solve?

Issue Number: close #50496

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

[ti-chi-bot]

This cherry pick PR is for a release branch and has not yet been approved by triage owners.
Adding the do-not-merge/cherry-pick-not-approved label.

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-01-25 05:35:02.219118018 +0000 UTC m=+1025343.783415723: ☑️ agreed by AilinKid.
• 2024-01-25 05:48:42.159887538 +0000 UTC m=+1026163.724185243: ☑️ agreed by hawkingrei.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release-7.6@52794d9). Click here to learn what that means.
The diff coverage is n/a.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-7.6     #50716   +/-   ##
================================================
  Coverage               ?   70.0336%           
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  Files                  ?       1436           
  Lines                  ?     419303           
  Branches               ?          0           
================================================
  Hits                   ?     293653           
  Misses                 ?     105357           
  Partials               ?      20293           

Flag	Coverage Δ
unit	70.0336% <0.0000%> (?)

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

Components	Coverage Δ
dumpling	54.0269% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	49.6793% <0.0000%> (?)

[AilinKid]

waiting for v7.6 unfreezing