br: compatible with and add integration test for partial index (#64434)

[ti-chi-bot]

This is an automated cherry-pick of #64434

What problem does this PR solve?

Issue Number: ref #62664

Problem Summary:
To be compatible with partial index for repairing ingest index after log restore

What changed and how does it work?

recognize the IndexInfo.ConditionExprString

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]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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Details

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (release-8.5-20260116-v8.5.5@db87a51). Learn more about missing BASE report.

Additional details and impacted files

@@                       Coverage Diff                        @@
##             release-8.5-20260116-v8.5.5     #65917   +/-   ##
================================================================
  Coverage                               ?   73.1805%           
================================================================
  Files                                  ?       1684           
  Lines                                  ?     470237           
  Branches                               ?          0           
================================================================
  Hits                                   ?     344122           
  Misses                                 ?     103196           
  Partials                               ?      22919           

Flag	Coverage Δ
integration	50.9245% <100.0000%> (?)
unit	64.8694% <0.0000%> (?)

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

Components	Coverage Δ
dumpling	52.9278% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	63.8155% <0.0000%> (?)

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[YangKeao]

lucky! no conflict.

[YangKeao]

/retest