planner: fix nulleq condition to calcalate index range (#56769)

[ti-chi-bot]

This is an automated cherry-pick of #56769

What problem does this PR solve?

Issue Number: close #56745

Problem Summary:

What changed and how does it work?

treat col<=>null as range scan instead of point get to avoid incorrect results. so we find it in the getPotentialEqOrInColOffset and should return -1. But this condition is wrong.

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 ✅

Please upload report for BASE (release-8.4@8af68d6). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-8.4     #56785   +/-   ##
================================================
  Coverage               ?   56.2339%           
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  Files                  ?       1751           
  Lines                  ?     628078           
  Branches               ?          0           
================================================
  Hits                   ?     353193           
  Misses                 ?     250994           
  Partials               ?      23891           

Flag	Coverage Δ
integration	36.8204% <100.0000%> (?)
unit	72.5049% <100.0000%> (?)

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

Components	Coverage Δ
dumpling	52.9478% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	52.4130% <0.0000%> (?)

[hawkingrei]

/retest

[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:

• 2024-10-22 14:56:15.838340893 +0000 UTC m=+362976.535131524: ☑️ agreed by hawkingrei.
• 2024-10-22 15:04:13.068528642 +0000 UTC m=+363453.765319271: ☑️ agreed by winoros.

[hawkingrei]

/retest