planner: fix tiflash path will be identified as table dual (#49338)

[ti-chi-bot]

This is an automated cherry-pick of #49338

What problem does this PR solve?

Issue Number: close #49285

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.

planner: fix tiflash path will be identified as table dual

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release-7.5@e62ed60). Click here to learn what that means.
The diff coverage is n/a.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-7.5     #50903   +/-   ##
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  Coverage               ?   71.9722%           
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  Files                  ?       1401           
  Lines                  ?     406779           
  Branches               ?          0           
================================================
  Hits                   ?     292768           
  Misses                 ?      94298           
  Partials               ?      19713           

Flag	Coverage Δ
unit	71.9722% <0.0000%> (?)

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

Components	Coverage Δ
dumpling	53.9913% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	53.2601% <0.0000%> (?)

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-02-01 13:09:42.226015473 +0000 UTC m=+1657423.790313177: ☑️ agreed by winoros.
• 2024-02-01 13:21:56.862436232 +0000 UTC m=+1658158.426733937: ☑️ agreed by hawkingrei.